Biomedical subjects

P D Walker

Publications and source records attributed to P D Walker.

At least 19 recordsLinked to original sources

PubMed2006

Is IgA nephropathy the commonest primary glomerulopathy among young adults in the USA?

Over the past decade, focal segmental glomerulosclerosis (FSGS) has emerged as the most common primary glomerulopathy in adults in the USA. However in our practice, we became aware of increased numbers of patients with IgA nephropathy (IgAN). In order to further examine this, a retrospective analysis of renal biopsy diagnoses from adults was done from our biopsy database. Adult renal biopsies received from 3/1/2001 to 2/28/2005 were analyzed to determine the frequency of common primary glomerulopathies, which included FSGS, IgAN, membranous nephropathy (MN), minimal change disease, and membranoproliferative glomerulonephritis Type I (MPGN). The patients were grouped as all adults (>or=20 years) and young adults (20-39 years). The distribution of common primary glomerulopathies among the two age groups, expressed as a percentage of all non-transplant diagnoses (n = 4,504), was IgAN 6.9/3.4%, FSGS 9.6/3.2%, MN 6.8/1.6%, minimal change disease 2.5/0.9%, MPGN 1.2/0.2%. IgAN was as common as FSGS in young adults in our biopsy population (IgAN/FSGS 154/143 1.08:1). IgAN was the most common primary glomerulopathy in young adult Caucasians (IgAN/FSGS 2.1:1). IgAN was also the most common cause of end-stage renal disease (ESRD) in young adult Caucasians. In contrast, IgAN was rare in African Americans in whom FSGS remains more common (FSGS/IgAN 9.7:1). These findings from a large renal biopsy referral center serving 24 Midwestern and Southern states suggest that IgAN may be the most common primary glomerulopathy and the most common cause of ESRD in young adult Caucasians in the USA.

Adult↗

PubMed2005

Failure of MK-801 to suppress D1 receptor-mediated induction of locomotor activity and striatal preprotachykinin mRNA expression in the dopamine-depleted rat.

N-methyl-D-aspartate receptor antagonism exerts suppressive influences over dopamine D1 receptor-mediated striatal gene expression and locomotor behavior in the intact rat. The present study examined the effects of the N-methyl-D-aspartate receptor antagonist MK-801 on locomotor activity and striatal preprotachykinin mRNA expression stimulated by the D1 agonist (+/-)6-chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide in rats with bilateral dopamine lesions. Two months after neonatal dopamine lesions with 6-hydroxydopamine, rats were challenged with (+/-)6-chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (1.0 mg/kg) 15 min after administration of the N-methyl-D-aspartate receptor antagonist MK-801 (0.1 mg/kg). In the intact rat, MK-801 prevented the induction of striatal preprotachykinin mRNA by D1 agonism. Similarly, direct infusion of (+/-)6-chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (3.0 microg) into the intact striatum produced an increase in locomotor activity that was suppressed by MK-801 (1.0 microg) co-infusion. In the dopamine-depleted rat, MK-801 (0.1 mg/kg) administered prior to (+/-)6-chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (1.0 mg/kg) increased, rather than suppressed, striatal preprotachykinin mRNA levels. Intrastriatal infusion of MK-801 (1.0 microg) failed to inhibit D1-mediated induction of motor activity in dopamine-depleted animals. Together, these data provide further support that N-methyl-D-aspartate receptor antagonists lose their ability to block D1-mediated behavioral activation following dopamine depletion. The activation, rather than suppression, of tachykinin neurons of the direct striatonigral pathway may play a facilitatory role in this mechanism.

Animals↗

PubMed2003

Combined intrastriatal dopamine D1 and serotonin 5-HT2 receptor stimulation reveals a mechanism for hyperlocomotion in 6-hydroxydopamine-lesioned rats.

Loss of dopaminergic innervation to the striatum increases the sensitivity of dopamine (DA) D1 and serotonin (5-HT) 5-HT2 receptor signaling. Previous work from our laboratory has shown that systemic co-administration of D1 and 5-HT2 receptor agonists leads to the synergistic overexpression of striatal preprotachykinin mRNA levels in the DA-depleted, but not intact animals. In the present study, we examined this mechanism as related to locomotor behavior. Adult male Sprague-Dawley rats were subject to bilateral i.c.v. 6-hydroxydopamine (6-OHDA; 200 microg in 10 microl/side) or vehicle (0.9% saline and 0.1% ascorbic acid). After 3 weeks, rats were tested for locomotor responses to bilateral intrastriatal infusions of vehicle (0.9% NaCl), the D1 agonist SKF82958 [(+/-)6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetra-hydro-(1H)-3-benzazepine hydrobromide; 0.1, 1.0 or 10.0 microg/side], the 5-HT2 agonist DOI [(+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane; 0.1, 1.0 or 10.0 microg/side] or subthreshold doses of DOI and SKF82958 (0.1 microg+0.1 microg in 0.8 microl/side). Rats with DA loss demonstrated supersensitive locomotor responses to SKF82958, but not DOI. Combined administration of subthreshold SKF82958 and DOI doses (0.1 microg+0.1 microg) synergistically increased locomotor behavior only in 6-OHDA-lesioned rats. These effects were blocked by either the D1 antagonist SCH23390 3-methyl-1-phenyl-2,3,4,5-tetrahydro-7-chloro-8-hydroxy-(1H)-3-benzazepine or the 5-HT2 antagonist ritanserin (each 1.0 microg in 0.8 microl/side). The results of this study suggest that the behavioral synergy induced by local co-stimulation of D1 and 5-HT2 receptors within the 6-OHDA-lesioned striatum may lead to hyperkinesias that can occur with continued pharmacological treatment of Parkinson's disease.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

NMDA receptor antagonism modifies the synergistic regulation of striatal tachykinin gene expression induced by dopamine D(1) and serotonin(2) receptor stimulation following neonatal dopamine depletion.

Co-application of SKF-38393 (dopamine D(1) agonist; 1 mg/kg) and DOI (serotonin(2) agonist; 1 mg/kg) induced a synergistic increase in striatal preprotachykinin (PPT) mRNA levels in adult rats 60 days after neonatal intracerebroventricular injection of 6-hydroxydopamine. This magnitude of response was not observed in intact (vehicle-injected) rats and was restricted to the dorsomedial (DM, 333+/-25% of lesion) subregion of the anterior striatum, with smaller increases observed in the dorsolateral striatum (DL, 206+/-26% of lesion). A single i.p. injection of MK-801 (NMDA antagonist; 0.1 mg/kg) administered prior to dopamine D(1) (D(1)) and serotonin(2) (5-HT(2)) receptor co-stimulation suppressed the synergistic regulation of PPT mRNA expression in the DM striatum, but also produced a large increase in PPT message levels within the DL striatum (321+/-17% of lesion). These data suggest that the synergistic regulation of PPT mRNA within the DM striatum induced by D(1)/5-HT(2) receptor co-stimulation in the dopamine lesioned rat is dependent on NMDA receptor activity. However, MK-801 may simultaneously potentiate striatal PPT mRNA expression by a separate mechanism due to the changed environment of the dopamine-depleted basal ganglia.

Animals↗

PubMed2001

Serotonin 2A receptor regulation of striatal neuropeptide gene expression is selective for tachykinin, but not enkephalin neurons following dopamine depletion.

Serotonin (5-HT) 2A receptor-mediated regulation of striatal preprotachykinin (PPT) and preproenkephalin (PPE) mRNAs was studied in adult rodents that had been subjected to near-total dopamine (DA) depletion as neonates. Two months following bilateral 6-hydroxydopamine (6-OHDA) lesion, PPT mRNA levels decreased 59-73% across dorsal subregions of the rostral and caudal striatum while PPE transcripts increased 61-94%. Four hours after a single injection of the serotonin 2A/2C receptor agonist, (+/-)-1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 1 mg/kg), PPT mRNA expression was significantly increased in DA-depleted rats across all dorsal subregions of the rostral and caudal striatum as compared to 6-OHDA-treated animals alone. In the intact rat, DOI did not influence PPT mRNA levels in the rostral striatum, but did raise expression in the caudal striatum where 5-HT2A receptors are prominent. DOI did not regulate PPE mRNA levels in any striatal sub-region of the intact or DA-depleted rat. Prior administration of the 5-HT2A/2C receptor antagonist, ritanserin (1 mg/kg) or the 5-HT2A receptor antagonist, ketanserin (1 mg/kg) completely blocked the DOI-induced increases in striatal PPT mRNA in both lesioned and intact animals. The ability of ketanserin to produce identical results as ritanserin suggests that 5-HT2A receptor-mediated regulation is selectively strengthened within tachykinin neurons of the rostral striatum which are suppressed by DA depletion. The selectivity suggests that 5-HT2A receptor upregulation following DA depletion is capable of regulating tachykinin biosynthesis without influencing enkephalin expression in striatal output neurons.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

MK-801 prevents dopamine D1 but not serotonin 2A stimulation of striatal preprotachykinin mRNA expression.

We examined dopamine (DA) and serotonin (5-HT) receptor-mediated influences on striatal preprotachykinin (PPT, tachykinin precursor) mRNA regulation in organotypic slice cultures. A 3 h exposure to SKF-38393 (10 microM, DA D1 agonist) or DOI (10 microM, 5-HT2 agonist) increased PPT mRNA levels to 196.4% and 154.0%, respectively. Responses to SKF-38393 were prevented by SCH-23390 (10 microM, D1 antagonist) whereas DOI-stimulated increases were prevented by ketanserin (10 microM, 5-HT2A antagonist). Since striatal tachykinin neurons also possess NMDA receptors that regulate gene expression, stimulation of PPT message levels was examined in the presence of MK-801, a non-competitive NMDA antagonist. Alone, MK-801 (10 nM) did not significantly alter basal PPT message levels. However, MK-801 prevented SKF-38393-stimulated increases in PPT mRNA expression while DOI-induced expression was not affected. These results provide evidence that D1 regulation of striatal tachykinin expression is dependent on NMDA-type glutamate neurotransmission while 5-HT2A regulation appears independent.

Animals↗

PubMed2001

Striatal preprotachykinin mRNA levels are regulated by stimulatory agents and dopamine D1 receptor manipulation in rodent organotypic slice cultures.

We have utilized an organotypic slice culture system to determine factors which directly influence the expression of striatal preprotachykinin (PPT) mRNA. Striatal slices were generated from 3-day-old male rat pups and cultured on Millicell-CM inserts in serum-containing media. Under these conditions, striatal PPT mRNA levels fell significantly (-55.7+/-6.2%) in slices cultured for 2 days in vitro (2DIV) as compared to slices placed in culture for 3 h (0DIV). However, striatal PPT mRNA expression did not decline further in 4DIV cultured slices (-59.6+/-7.1%). When 2DIV slices were exposed to combined high potassium (K(+), 10 mM) and forskolin (10 microM) stimulation for 3 h, PPT mRNA levels were increased within areas of the brain normally associated with tachykinin production. Application of the dopamine (DA) D1 receptor agonist SKF-38393 (10 microM) at 2DIV for 3 h also increased (+162.9+/-28.9%) PPT mRNA expression, but increases were localized within the striatum. SKF-38393-stimulated increases were completely blocked by the D1 antagonist SCH-23390 (10 microM), which alone had no effect on mRNA levels. However, a 3-h incubation with SKF-38393 on 0DIV slice cultures did not affect PPT mRNA expression whereas SCH-23390 decreased PPT message levels (-24.5+/-5.4%). These findings indicate that tachykinin gene expression is inducible within slice culture preparations and that the maintenance of normal striatal PPT mRNA levels depends on DA D1 receptor tone.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed2001

Distribution of serotonin 2A and 2C receptor mRNA expression in the cervical ventral horn and phrenic motoneurons following spinal cord hemisection.

Cervical spinal cord injury leads to a disruption of bulbospinal innervation from medullary respiratory centers to phrenic motoneurons. Animal models utilizing cervical hemisection result in inhibition of ipsilateral phrenic nerve activity, leading to paralysis of the hemidiaphragm. We have previously demonstrated a role for serotonin (5-HT) as one potential modulator of respiratory recovery following cervical hemisection, a mechanism that likely occurs via 5-HT2A and/or 5-HT2C receptors. The present study was designed to specifically examine if 5-HT2A and/or 5-HT2C receptors are colocalized with phrenic motoneurons in both intact and spinal-hemisected rats. Adult female rats (250-350 g; n = 6 per group) received a left cervical (C2) hemisection and were injected with the fluorescent retrograde neuronal tracer Fluorogold into the left hemidiaphragm. Twenty-four hours later, animals were killed and spinal cords processed for in situ hybridization and immunohistochemistry. Using (35)S-labeled cRNA probes, cervical spinal cords were probed for 5-HT2A and 5-HT2C receptor mRNA expression and double-labeled using an antibody to Fluorogold to detect phrenic motoneurons. Expression of both 5-HT2A and 5-HT2C receptor mRNA was detected in motoneurons of the cervical ventral horn. Despite positive expression of both 5-HT2A and 5-HT2C receptor mRNA-hybridization signal over phrenic motoneurons, only 5-HT2A silver grains achieved a signal-to-noise ratio representative of colocalization. 5-HT2A mRNA levels in identified phrenic motoneurons were not significantly altered following cervical hemisection compared to sham-operated controls. Selective colocalization of 5-HT2A receptor mRNA with phrenic motoneurons may have implications for recently observed 5-HT2A receptor-mediated regulation of respiratory activity and/or recovery in both intact and injury-compromised states.

Animals↗

PubMed2001

Neonatal dopamine depletion reveals a synergistic mechanism of mRNA regulation that is mediated by dopamine(D1) and serotonin(2) receptors and is targeted to tachykinin neurons of the dorsomedial striatum.

It has been hypothesized that dopamine(D1) and serotonin(2) receptors become sensitized to agonist-mediated regulation of gene expression following loss of dopaminergic innervation to the striatum. We have previously demonstrated that the combined administration of dopamine(D1) and serotonin(2) receptor agonists to dopamine-depleted adult rats induced preprotachykinin mRNA expression within the periventricular rostral striatum to levels which were significantly different than what could be elicited by either agonist alone. In the present study, we have determined that this phenomenon is revealed only after dopamine depletion. In addition, it is targeted primarily to tachykinin producing neurons of the dorsomedial striatum and is dependent on both dopamine(D1) and serotonin(2) receptor activation. Preprotachykinin mRNA levels in the intact striatum were unaltered 4 h following an i.p. injection of either SKF-38393 (1 mg/kg, dopamine(D1) partial agonist) or (+/-)-1-(4-Iodo-2,5-dimethoxyphenyl)-2-aminopropane (DOI 1 mg/kg, serotonin(2) agonist). However, the combined application of both agonists increased (+44%) preprotachykinin message levels, but these changes were restricted to the dorsomedial striatum. In adult animals depleted of dopamine as neonates, striatal preprotachykinin mRNA expression was reduced by approximately 50%. From this lowered level of basal expression, DOI or SKF-38393 raised preprotachykinin mRNA levels within the dorsomedial, but not the dorsolateral striatum. Furthermore, co-stimulation of dopamine(D1) and serotonin(2) receptors produced a nearly four-fold induction of preprotachykinin message levels in the dorsomedial striatum that was significantly greater than either agonist alone. Application of both agonists also elevated preprotachykinin mRNA expression within the dorsolateral striatum, but to a lesser extent. All increases in preprotachykinin mRNA resulting from co-application of SKF-38393 and DOI were prevented by pretreatment with either SCH-23390 (1 mg/kg, dopamine(D1) antagonist) or ritanserin (1 mg/kg, serotonin(2) antagonist). Alternately, preproenkephalin mRNA expression was unaffected by dopamine(D1) receptor stimulation, but was slightly elevated by DOI or both agonists together (42-58%) in intact animals. However, neither agonist treatment in this experiment significantly altered preproenkephalin mRNA expression in the dopamine-depleted striatum which was elevated in response to dopamine lesion alone. Dopamine depletion appears to promote a synergistic interaction between dopamine(D1) and serotonin(2) receptors that leads to enhanced expression of striatal preprotachykinin mRNA levels. The localization of this phenomenon to tachykinin neurons of the direct striatonigral pathway specifically within the dorsomedial regions of the rostral striatum may be relevant to the problem of dyskinetic behaviors which arise during the pharmacological treatment of movement disorders.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

Polyoma viral infection in renal transplantation: the role of immunosuppressive therapy.

BACKGROUND: Polyoma virus infection in renal transplant recipients has been observed with increasing frequency in recent years. Renal allograft involvement in this condition may occur as a result of primary infection or secondary to reactivation of the latent virus. Interstitial nephritis, ureteric stenosis, rise in serum creatinine and allograft function loss have been attributed to this viral infection. METHODS: In this study we reviewed our experience with 8 patients who developed polyoma viral infection confirmed by allograft biopsy. All patients were receiving mycophenolate mofetil as part of the immunosuppression and 7 of the 8 patients were on tacrolimus. All patients have biopsy proven polyoma viral infection. The following therapeutic maneuvers were carried out following the diagnosis of polyoma viral infection: 1) stopping mycophenolate and 2) switching tacrolimus to cyclosporine or reducing the tacrolimus dose to adjust it at a lower therapeutic trough level. The clinical course and outcome of our patients were reviewed in relation to manipulation of immunosuppressive medications. RESULTS: The incidence of this infection in our transplant program in the last 3 yr was 5.3%. Seventy-five percent of the patients had at least one rejection episode and 63% had more than one rejection episode. The main risk factor for the development of polyoma viral infection was related to the intensity of immunosuppression. The use of antirejection therapy after histological diagnosis of polyoma virus infection was not associated with improvement of renal function despite the histological appearance of acute rejection. Thus, the interstitial nephritis associated with polyoma viral infection appears to be an inflammatory response to the virus rather than acute rejection. Six out of the 8 patients stabilized renal function with reduction in immunosuppression. CONCLUSIONS: Reduction in immunosuppression was associated with the stabilization of renal function when instituted early. However, these patients were left with a degree of allograft dysfunction and their outcome may be significantly compromised. The lack of effective antiviral therapy for polyoma virus may limit the use of newer and more potent immunosuppressive medications.

Acute Disease↗

PubMed2000

Stimulated serotonin release from hyperinnervated terminals subsequent to neonatal dopamine depletion regulates striatal tachykinin, but not enkephalin gene expression.

Dopamine (DA) depletion in neonatal rodents results in depressed tachykinin and elevated enkephalin gene expression in the adult striatum (STR). Concurrently, serotonin (5-HT) fibers sprout to hyperinnervate the DA-depleted anterior striatum (A-STR). The present study was designed to determine if increased 5-HT release from sprouted terminals influences dysregulated preprotachykinin (PPT) and preproenkephalin (PPE) mRNA expression in the DA-depleted STR. Three-day-old Sprague-Dawley rat pups received bilateral intracerebroventricular injections of vehicle or the DA neurotoxin 6-hydroxydopamine (6-OHDA, 100 microg). Two months later, rats received a single intraperitoneal injection of vehicle or the acute 5-HT releasing agent p-chloroamphetamine (PCA; 10 mg/kg). Rats were killed 4 h later and striata processed for monoamine content by HPLC-ED and mRNA expression by in situ hybridization within specific subregions of the A-STR and posterior striatum (P-STR). 6-OHDA treatment severely (>98%) reduced striatal DA levels, while 5-HT content in the A-STR was significantly elevated (doubled), indicative of 5-HT hyperinnervation. Following 6-OHDA, PPT mRNA levels were depressed 60-66% across three subregions of the A-STR and 52-59% across two subregions of the P-STR, while PPE mRNA expression was elevated in both the A-STR (50-62%) and P-STR (55-82%). PCA normalized PPT mRNA levels in all regions of the DA-depleted A-STR and P-STR, yet did not alter PPE levels in either dorsal central or medial regions from 6-OHDA alone, but reduced PPE to control levels in the dorsal lateral A-STR. These data indicate that increased 5-HT neurotransmission, following neonatal 6-OHDA treatment, primarily influences PPT-containing neurons of the direct striatal output pathway.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2000

Acute rejection presenting as nephrotic syndrome.

BACKGROUND: Early diagnosis and treatment of acute rejection is important to prevent continued renal injury. Acute rejection most commonly presents with asymptomatic rise in serum creatinine. Proteinuria associated with acute rejection is well established; however, there is limited documentation of the presentation of acute rejection as nephrotic syndrome in the literature. METHODS AND RESULTS: We report a renal transplant patient who presented with early onset nephrotic syndrome without change in serum creatinine, whose allograft biopsy confirmed acute glomerulitis and vascular rejection. Treatment of the acute rejection was accompanied by resolution of the nephrotic syndrome. A second episode of acute rejection was also manifested as nephrotic range proteinuria. CONCLUSION: The nephrotic syndrome in early post-transplantation period should prompt a work-up for acute rejection even in the absence of the common findings of this complication.

Acute Disease↗

PubMed2000

Cyclic AMP regulates substance P expression in developing and mature spinal sensory neurons.

The tachykinin, substance P, has long been associated with transmission of noxious stimuli. However, relatively little is known about signal transduction pathways subserving peptidergic regulation in sensory neurons. To investigate whether cyclic AMP (cAMP) could be a potential second messenger subserving substance P expression, dorsal root ganglion neurons were grown in culture in the presence of agents that increase content of cAMP. In developing neurons, forskolin increased substance P content and survival almost threefold. Anti-nerve growth factor (NGF) blocked the effect of NGF but not forskolin, suggesting that increased cAMP acts directly and not via increased secretion of NGF from Schwann cells and fibroblasts. In adult neurons, which do not require supplemental trophic factors for survival, NGF and forskolin had similar effects on substance P levels. Neither agent had any effect on somatostatin content of either developing or mature sensory neurons. 8-bromo cAMP and isobutyl methylxanthine duplicated the action of forskolin. Further, all three agents increased expression of preprotachykinin mRNA. Forskolin appeared to increase both total and neuron-specific expression of message as well as the number of neurons expressing mRNA. Our results suggest that cAMP directly regulates substance P content in sensory neurons from adult and neonatal rats.

1-Methyl-3-isobutylxanthine↗

PubMed2000

Serotonin 2A and 2C receptor biosynthesis in the rodent striatum during postnatal development: mRNA expression and functional linkage to neuropeptide gene regulation.

The present study was designed to determine if there are region-specific differences in serotonin (5-HT) neurotransmission and 5-HT receptor expression that may limit the stimulatory effects of the 5-HT releaser p-chloroamphetamine (pCA) on striatal neuropeptide gene expression to the posterior striatum (P-STR) during postnatal maturation. Sprague-Dawley rat brains from postnatal days (PND) 1-35 were processed for 5-HT(2A) and 5-HT(2C) receptor mRNA expression by in situ hybridization and monoamine analysis by HPLC. Within the P-STR, 5-HT(2A) receptor mRNA expression reached young adult (PND 35) levels by PND 3, while levels in the A-STR were significantly less (range: 1.43 +/- 0.219-6. 36 +/- 0.478) than P-STR (5.36 +/- 0.854-12.11 +/- 1.08) at each respective age throughout the time course. 5-HT(2C) receptor mRNA expression reached young adult levels at PND 7 in the A-STR and by PND 3 in the P-STR. At each PND age 5-HT(2C) receptor mRNA levels within the P-STR were significantly less (6.23 +/- 1.02-12.32 +/- 0.427) than the A-STR (7.31 +/- 1.65-26.84 +/- 2.24). 5-HT content increased across the developmental time course within the P-STR (5.01 +/- 0.327-15.7 +/- 1.03 ng/mg protein) and A-STR (2.97 +/- 0. 223-11.2 +/- 0.701 ng/mg protein). Four hours following injection (i. p.) of pCA (10 mg/kg), preprotachykinin (PPT) mRNA levels increased 89% in the P-STR but not the anterior (A-STR) striatum of the 3-week-old rat, which were prevented by preinjection (30 min, i.p.) of the 5-HT(2) receptor antagonist ritanserin (1 mg/kg). Together, these data suggest that faster maturity of 5-HT(2A) receptor expression in the P-STR may be sufficient to convey the region-specific acute stimulatory effects of pCA on PPT mRNA transcription in the developing rodent striatum. These results provide further evidence that the influence of 5-HT on neuropeptide gene expression is far stronger in caudal vs. rostral striatal regions during postnatal development.

Animals↗

PubMed2000

Feasibility study of multicentre comparison of NHS hospital pharmacy computer data.

AIMS: This study aims to determine the feasibility of collecting, collating and analysing drug expenditure data from a sample of acute hospitals in England. METHODS: The hospital pharmacy computer system was used to report on drug expenditure from 16 hospitals throughout England for a 2 year period. These data were analysed as a whole and hospital episode statistics were correlated to hospital drug costs. RESULTS: Hospital outpatient costs were found to be approximately one third of hospital inpatient costs. Cardiovascular drugs accounted for the greatest increase in expenditure for both inpatients and outpatients (25%). The most expensive therapeutic area of drug use across all sites was anti-infectives. The average daily number of occupied beds explained 55% of the variation in inpatient expenditure and the number of outpatient (including Accident and Emergency) attendances explained 60% of the outpatient drug expenditure. CONCLUSIONS: This project has confirmed the feasibility of collecting, collating and analysing hospital drug expenditure and identified some interesting patterns and trends in hospital drug use. Hospital activity is reflected in hospital drug costs.

Clinical Pharmacy Information Systems↗

PubMed2000

Real-time analysis of preprotachykinin promoter activity in single cortical neurons.

Technological limitations have hindered the study of gene elements regulating transcription within CNS neurons. In the present stuides, rat cortical brain slices endogenously expressing the preprotachykinin (PPT) gene were transfected with gene constructs encompassing green fluorescent protein (GFP) under the control of the PPT promoter. These slices were maintained in organotypic culture so that the fluorescence intensity within individual living cells could be quantified using laser scanning confocal microscopy before and after application of stimulatory agents. Combined treatment with forskolin and elevated potassium significantly increased expression of both endogenous PPT mRNA and the PPT promoter-GFP construct. The ability to follow fluorescence changes within single neurons in real time offers a powerful "within-subject" experimental approach for analysis of neural gene promoters.

Animals↗

PubMed2000

Acute rejection-associated tubular basement membrane defects and chronic allograft nephropathy.

BACKGROUND: Acute rejection is a major risk factor for chronic allograft nephropathy, although the link(s) between these events is not understood. The hypothesis of this study is that alterations in tubular basement membranes (TBMs) that occur during acute rejection may be irreversible and thereby play a role in the development of chronic allograft nephropathy. METHODS: Fourteen renal transplant patients were selected, each having had two or more biopsies performed (42 total). All biopsies were scored for acute and chronic rejection using Banff 1997 criteria. The initial biopsy showed only acute interstitial rejection (type I rejection). No biopsies contained significant chronic arterial lesions of chronic vascular rejection. The entire cortex was examined on Jones methenamine silver-stained sections at x400 for interruption in TBM staining. The number of tubules with TBM abnormalities was counted, and the renal cortical area was measured by image analysis. Periodic acid-Schiff/immunoperoxidase stain was performed on 12 acute rejection biopsies stained for laminin, cytokeratin 7, CD3, CD20, and CD68. Controls consisted of 11 biopsies (8 negative for rejection and 3 acute tubular necrosis). RESULTS: Numerous TBM alterations in silver staining were identified as being associated with acute rejection and tubulitis, consisting of abrupt TBM discontinuities and/or extreme attenuation with segmental or complete absence of TBM. A loss of TBM matrix proteins was confirmed by absent laminin staining in areas of acute rejection and tubulitis. There was herniation of tubular cells into the interstitium through TBM defects confirmed by cytokeratin staining. The TBM defects were spatially associated with inflammatory cells, particularly macrophages. When the biopsies were divided into two groups, <10 and> 10 TBM breaks/mm2, there were statistically significant morphologic and clinical correlations. The number of TBM disruptions correlated with the serum creatinine at the time of biopsy, a combined Banff t + i score, the difference in tubular atrophy between the initial and most recent biopsy and the difference between the nadir creatinine and most recent creatinine. CONCLUSION: Damage to TBM develops in acute rejection as a consequence of interstitial inflammation and tubulitis. These lytic events correlate with the later development of clinical and morphologic evidence of chronic injury in the absence of arterial injury of chronic rejection. We suggest that chronic allograft nephropathy may have an inflammatory interstitial origin.

Acute Disease↗

PubMed2000

Evidence for peroxynitrite formation in renal ischemia-reperfusion injury: studies with the inducible nitric oxide synthase inhibitor L-N(6)-(1-Iminoethyl)lysine.

Reactive oxygen species are suggested to participate in ischemia-reperfusion (I-R) injury. However, induction of inducible nitric oxide synthase (iNOS) and production of high levels of nitric oxide (NO) also contribute to this injury. NO can combine with superoxide to form the potent oxidant peroxynitrite (ONOO(-)). NO and ONOO(-) were investigated in a rat model of renal I-R injury using the selective iNOS inhibitor L-N(6)-(1-iminoethyl)lysine (L-NIL). Sprague-Dawley rats were subjected to 40 min of bilateral renal ischemia followed by 6 h of reperfusion with or without L-NIL administration. Control animals received a sham surgery and had plasma creatinine values of 0.4 +/- 0.1 mg/dl. I-R surgery significantly increased plasma creatinine levels to 1.9 +/- 0.3 mg/dl (P <.05) and caused renal cortical necrosis. L-NIL administration (3 mg/kg) in animals subjected to I-R significantly decreased plasma creatinine levels to 1.2 +/- 0.10 mg/dl (P <.05 compared with I-R) and reduced tubular damage. ONOO(-) formation was evaluated by detecting 3-nitrotyrosine-protein adducts, a stable biomarker of ONOO(-) formation. Immunohistochemistry and HPLC revealed that the kidneys from I-R animals had increased levels of 3-nitrotyrosine-protein adducts compared with control animals. L-NIL-treated rats (3 mg/kg) subjected to I-R showed decreased levels of 3-nitrotyrosine-protein adducts. These results support the hypothesis that iNOS-generated NO mediates damage in I-R injury possibly through ONOO(-) formation.

Animals↗