The patient care delivery mode at Mercy Medical Center: a licensed caregiver model.
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Academic Medical Centers↗
Biomedical subjects
R Raymond
Publications and source records attributed to R Raymond.
Regional changes in beta1 thyroid hormone receptor immunoreactivity in rat brain after thyroidectomy.
Quantitative [125I]protein G-based immunohistochemistry was used to map the distribution of beta1 thyroid hormone receptor (TRbeta1) in normal and thyroidectomized adult rat brain, using a previously characterized polyclonal antibody. The distribution of TRbeta1-like immunoreactivity in normal brain was largely but not perfectly concordant with previous accounts of TRbeta1 mRNA distribution in rat brain. Thyroidectomy resulted in increased immunolabeling in most brain regions (mean increase: 14%, range: -4% to +25%), with statistically significant effects being observed in 9 of the 36 brain regions examined. Brain regions showing the most pronounced effects included the habenular nucleus (+22%), the oriens layer of the hippocampal CA3 region (+24%), and the lateral geniculate nucleus of the thalamus (+23%). These results demonstrate that the TRbeta1 protein in brain is capable of plastic changes in response to adult-onset alterations in TH levels. The observed pattern of brain regional receptor changes following thyroidectomy may provide clues for functional effects of thyroid function alterations in adults.
Age Factors↗
Alterations in N-methyl-D-aspartate receptor binding in dystonic hamster brains.
The genetically dystonic hamster is an animal model of idiopathic dystonia that displays sustained abnormal movements and postures either spontaneously or in response to mild environmental stimuli. Previous pharmacological studies have shown that competitive and non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists exert potent antidystonic activity in this model, indicating that abnormal NMDA receptor function may be involved in the pathophysiology of this movement disorder. Autoradiographic analysis of NMDA receptor density in 67 brain regions, using the ligand [3H] N-(1-[2-thienyl]cyclohexyl)3,4-piperidine, which binds to the phencyclidine (PCP) site in the ion channel of the NMDA receptor channel complex, revealed that NMDA receptor binding is not substantially altered in dystonic hamster brains compared to age-matched controls. Nevertheless, there was a tendency towards enhanced binding during a dystonic attack in several regions, including a 25% increase in the ventrolateral thalamic nucleus (P < 0.05), which may be associated with altered basal ganglia output. While the data do not indicate widespread abnormalities in the PCP site of the NMDA complex, they do not exclude the possibility of more pronounced changes at other regulatory binding sites of the NMDA complex or other types of glutamate receptors in dystonia.
Animals↗
The pharmacokinetics of pravastatin in patients on chronic hemodialysis.
OBJECTIVE: The single-dose and steady-state pharmacokinetics of the HMG CoA reductase inhibitor pravastatin and its two metabolites, SQ 31,906 and SQ 31,945, were evaluated in 12 hemodialysis patients. A single 20-mg i.v. dose was employed, followed by daily oral dosing of 20 mg over four hemodialysis intervals. RESULTS: No statistical differences in the pharmacokinetics of pravastatin or SQ 31,906 were evident when comparing the first and last days of oral dosing with pravastatin. The pharmacokinetic parameters of pravastatin and SQ 31,906 were similar to those of healthy volunteers. SQ 31,945, the inactive polar metabolite, did accumulate in dialysis patients, as evidenced by an accumulation index of 1.7 +/- 1.0. Although metabolic clearance is the predominant mode of elimination of pravastatin, hemodialysis clearances of pravastatin, SQ 31,906 and SQ 31,945 will contribute to total body clearance since dialytic clearance ranged from 40 to 80 ml.min-1. CONCLUSION: Pravastatin can be safely administered in the usual dosages to subjects with renal failure on hemodialysis and no change in dosing is necessary.
Administration, Oral↗
The effect of sorivudine on dihydropyrimidine dehydrogenase activity in patients with acute herpes zoster.
OBJECTIVE: Bromovinyl-uracil (BVU) is the principal metabolite of sorivudine, a potent anti-zoster nucleoside. BVU binds to, and irreversibly inhibits, the enzyme dihydropyrimidine dehydrogenase (DPD). The objective of this study was to assess the time course of recovery of DPD activity after oral administration of sorivudine in patients with herpes zoster and to correlate restoration of DPD activity and levels of uracil with the elimination of sorivudine and its metabolite BVU from the circulation. METHODS: Sorivudine was given orally as 40 mg once-daily doses for 10 consecutive days to a total of 19 patients with herpes zoster. Serum sorivudine, BVU, and circulating uracil and DPD activity in peripheral blood mononuclear cells (PBMCs) were determined before, during, and after administration of sorivudine. RESULTS: BVU was eliminated from the circulation within 7 days after the last sorivudine dose. DPD activity in PBMCs, which was completely suppressed in 18 of the 19 subjects and markedly suppressed in the remaining subject during administration of sorivudine, recovered to baseline levels within 19 days after the last dose of sorivudine in all subjects and within 14 days in all but one of the subjects. The restoration of DPD activity was temporally associated with elimination of BVU from the circulation. The elevated uracil concentrations produced by inhibition of DPD activity fell rapidly after cessation of sorivudine administration and also were temporally associated with elimination of BVU from the circulation. The time course of recovery of DPD activity in three patients with renal impairment was similar to that of the other subjects. CONCLUSIONS: This study indicates that sorivudine therapy is associated with a profound depression of DPD activity. Recovery of DPD activity occurred within 4 weeks of the completion of sorivudine therapy, which indicates that fluorinated pyrimidines may be safely administered 4 weeks after completion of sorivudine therapy.
Acute Disease↗
Insulin improves survival in a canine model of acute beta-blocker toxicity.
STUDY OBJECTIVE: To compare the efficacy of a novel antidote, insulin, with standard treatments, glucagon and epinephrine, in a canine model of acute beta-blocker toxicity. METHODS: Anesthetized dogs were fitted with instruments by means of thoracotomy and vascular cutdown for multiple cardiodynamic, hemodynamic, metabolic, and electrical measures. After basal measurements were taken, animals received intravenous propranolol (.25 mg/kg/minute) continuously for the remainder of the experiment. Toxicity was defined as a 25% decrease in the product of heart rate times mean blood pressure. Thirty minutes after the development of toxicity, toxic measures were taken (treatment 0 minutes), and then the animals (n = 6 each group) received either sham (saline solution), insulin (4 IU/minute with glucose clamped), glucagon (50 micrograms/kg bolus, then 150 micrograms/kg/hour infusion), or epinephrine (1 microgram/kg/minute). Animals were monitored until death or for 240 minutes. RESULTS: Propranolol decreased contractility, left ventricular pressure, and systemic blood pressure, and resulted in death of all sham-treated animals by 150 minutes. Six of six insulin-treated, four of six glucagon-treated, and one of six epinephrine-treated animals survived. Survival was greater for insulin-treated animals, compared with either glucagon-treated (P < .05) or epinephrine-treated animals (P < .02) by the log-rank test. Insulin-treated animals were characterized by improved cardiodynamics and hemodynamics, increased myocardial glucose uptake, and decreased serum potassium. CONCLUSION: Insulin is a superior antidote compared with glucagon or epinephrine in an anesthetized canine model of acute beta-blocker toxicity.
Acute Disease↗
Regulation of gene expression for tyrosine hydroxylase in oxygen sensitive cells by hypoxia.
Carotid body type I cells and the O2 sensitive pheochromocytoma (PC12) cells release dopamine during hypoxia. Reduced O2 tension causes inhibition of an outward rectifying the O2-sensitive potassium (K) channel in the O2-sensitive pheochromocytoma (PC12) cell line, which leads to membrane depolarization and increased intracellular free Ca2+. We found that removal of Ca2+ from the extracellular milieu, inhibition of voltage-dependent Ca2+ channels, and chelation of intracellular Ca2+ prevents full activation of the TH gene expression during hypoxia. These findings suggest that membrane depolarization and regulation of intracellular free Ca2+ are critical signal transduction events that regulate expression of the TH gene in PC12 cells during hypoxia. Gene expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in the biosynthesis of dopamine, is stimulated by reduced O2 tension in both type I cells and PC12 cells. The increase in TH gene expression in PC12 cells during hypoxia is due to increases in both the rate of transcription and mRNA stability. Analysis of reporter-gene constructs revealed that increased transcription of the TH gene during hypoxia is regulated by a region of the proximal promoter that extends from -284 to -150 bases, relative to the transcription start site. This region of the gene contains a number of cis-acting regulatory elements including AP1, AP2 and hypoxia-inducible factor (HIF-1). Competition assays revealed that hypoxia-induced binding occurs at both the AP1 and HIF-1 sites. Results from super-shift and shift Western assays showed that a heterodimer consisting of c-Fos and JunB binds to the AP1 site during hypoxia. Mutagenesis experiments revealed that the AP1 site is required for increased transcription of the TH gene during hypoxia. We also found that the genes that encode the c-Fos and JunB transcription factor proteins are regulated by reduced O2 tension.
Animals↗
Regulation of tyrosine hydroxylase gene expression during hypoxia: role of Ca2+ and PKC.
Gene expression for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, is regulated by reductions in oxygen tension (hypoxia). Hypoxia-induced regulation of the TH gene is due to the binding of specific transcription factors to specific sites on the 5' flanking region of the gene. The purpose of this study was to identify the second messenger system(s) responsible for regulation of the TH gene during hypoxia. Fura-2 fluorescence imaging of rat pheochromocytoma (PC12) cells, an O2-sensitive cell line, revealed that there is an increase in cytosolic calcium (Ca2+) associated with exposure to hypoxia. Based on the evidence that the transcription factors that bind to the TH promoter during hypoxia can also be induced by elevations in cytosolic Ca2+, the role of Ca2+ in the hypoxic regulation of the TH gene was explored. To assay the effect of hypoxia on TH gene expression, Northern blot analyses of total RNA were performed on PC12 cells exposed to hypoxia in the presence or absence of specific inhibitors. The addition of the L-type calcium channel blockers nifedipine or verapamil caused partial inhibition of the hypoxia-induced increase in TH mRNA. The increase in cytosolic Ca2+ during hypoxia was also only partially inhibited by addition of nifedipine. Importantly, chelation of extracellular Ca2+ completely inhibited the increase in TH mRNA by hypoxia. Pretreatment of PC12 cells with BAPTA/AM, an intracellular Ca2+ chelator, inhibited the hypoxic induction of TH gene expression in a dose-dependent manner. Addition of chelerythrine chloride (CHL), a protein kinase C inhibitor, to the media before exposure to hypoxia also resulted in an inhibition of TH induction by hypoxia. These results suggest that hypoxia regulates TH gene expression by a mechanism that is dependent on influx of calcium from the extracellular stores, partially but not exclusively through the L-type calcium channels. These results further suggest that a member of the PKC family is essential for this regulation.
Alkaloids↗
Measurement of 2,4-toluenediamine in urine and serum samples from women with Même or Replicon breast implants.
The objective of this matched case-control study was to determine whether women with Même or Replicon polyurethane-covered silicone breast implants are exposed to clinically significant levels of free 2,4-TDA from biodegradation of the polyurethane foam. Urine and serum samples were obtained from 61 patients with Même or Replicon breast implants and 61 controls on two separate occasions separated by 10 +/- 3 days. Free TDA was analyzed by gas chromatography combined with negative chemical ionization mass spectrometry with lower limit of quantitation in both urine and serum of 10 pg/ml. The results were correlated with the length of time since implantation. No patients or controls had detectable free 2,4-TDA in their sera. Thirty patients had quantifiable levels of free 2,4-TDA, and 18 had detectable levels in their urine. Controls had no quantifiable levels, but 7 subjects had detectable levels. The biodegradative half-life of the polyurethane foam was estimated to be 2 years. A risk assessment using the cancer potency estimate calculated by the FDA from rat data and the National Academy of Sciences methodology provided a theoretical lifetime risk of approximately one in one million. It was concluded that the polyurethane foam cover on the Même and Replicon breast implants biodegrades. The risk assessment of approximately one in one million derived from this study strengthens earlier conclusions by the Health Protection Branch (Canada) that there is no significant risk of cancer from exposure to the 2,4-TDA formed from this biodegradation.
Adult↗
The effect of hypertonic sodium and dantrolene on propranolol cardiotoxicity.
OBJECTIVE: To evaluate whether measures that lower cytosolic calcium (Ca) can reverse propranolol (PROP) toxicity in the isolated, perfused rat heart. METHODS: Isolated rat hearts were perfused on a Langendorff apparatus with Krebs-Henseleit-bicarbonate (KHB) buffer solution. Toxicity was produced by perfusing the hearts with PROP (5 micrograms/mL) for 30 minutes. Subsequently, the hearts were treated for 30 minutes with buffer containing PROP plus experimental treatment. Three treatments were chosen: hypertonic sodium (Na) (160 mmol), to stimulate Na-Ca exchange, dantrolene (DAN) (10 mumol), to inhibit Ca release from sarcoplasmic reticulum, and combined hypertonic Na and DAN. The hearts were paced after 20 minutes of treatment. Heart rate (HR), left ventricular peak systolic pressure (LVP), the first derivative of LVP (dP/dt), and coronary flow were measured. RESULTS: PROP decreased HR and rendered the hearts refractory to pacing. PROP did not alter dP/dt. PROP increased LVP consistent with increased cytosolic Ca. Combined hypertonic Na and DAN treatment restored the ability to pace PROP-toxic hearts to the basal HR. Individually, hypertonic Na or DAN treatment partially restored the ability to pace toxic hearts. As experimental treatments increased HR, dP/dt and LVP decreased, consistent with decreased cytosolic Ca availability. CONCLUSION: These data are consistent with the hypothesis that bradycardia during beta-blocker cardiotoxicity is mediated by altered Ca homeostasis.
Adrenergic beta-Antagonists↗
Pharmacokinetics and safety of a single dose of stavudine (d4T) in patients with severe hepatic impairment.
This open-label study enrolled five subjects with biopsy-proven cirrhosis and moderate to severe hepatic impairment (Child-Pugh classification grade B or C) and five age- and gender-matched controls. All subjects received a single 40-mg oral dose of stavudine (d4T). Stavudine pharmacokinetics in subjects with hepatic impairment were similar to those in age- and gender-matched control subjects and were not substantially different from those previously observed in human immunodeficiency virus-infected patients. Based on these findings, stavudine use does not require modification of the dose or dosing interval for patients with liver disease.
Administration, Oral↗
The effects of extracellular ions on beta-blocker cardiotoxicity.
The mechanism of beta-blocker induced cardiotoxicity is poorly understood. One possible explanation is that beta-blockers induce ion dyshomeostasis, resulting in cardiac hyperpolarization. The intent of this study was to determine if modifying extracellular ions would reverse cardiotoxicity from two beta-blockers: propranolol (PROP) and atenolol (ATEN). Two treatments were studied: low extracellular K+ and high extracellular Na+. Isolated rat hearts were perfused on a Langendorff apparatus with Krebs-Henseleit- Bicarbonate buffer (KHB) solution. Toxicity (Tox) was induced by perfusing hearts for 30 min with KHB + PROP [5 microgram/ml] or KHB + ATEN [2.5 mg/ml]. Subsequently, hearts were perfused with KHB containing either PROP or ATEN, but modified by lowering K+ [2.3 mM] or raising Na+ [160 mM] for a 30-min treatment (Tx) period. Hearts were paced near the end of treatment. Cardiodynamics were monitored via a balloon-tipped catheter in the left ventricle. The first derivative of LV pressure (dP/dt) with respect to time served as our index of myocardial performance. Tx groups were as follows: (1) KHB only, (2) PROP only, (3) PROP + K, (4) PROP + Na, (5) ATEN only, (6) ATEN 4 K, and (7) ATEN + Na. PROP induced negative chronotropic effects and rendered the hearts refractory to pacing. ATEN demonstrated similar chronotropic toxicity plus decreased myocardial contractility. Tx with low extracellular K+ and high extracellular Na+ increased HR and restored the ability to pace, thereby reversing toxicity. These data suggest that beta-blocker toxicity is mediated via hyperpolarization.
Adrenergic beta-Antagonists↗
Regulation of ionic conductances and gene expression by hypoxia in an oxygen sensitive cell line.
We have shown that the PC12 cell line is an excellent model system for investigations of the molecular and cellular processes involved in O2-chemosensitivity. We have identified an O2-sensitive K channel in this cell line that mediates membrane depolarization, an increase in intracellular free Ca2+, and dopamine release during hypoxia. We also presented evidence which shows that expression of the gene for tyrosine hydroxylase, the rate-limiting enzyme in dopamine biosynthesis, is stimulated by reduced O2 tension in PC12 and type I carotid body cells. In addition, we have successfully identified the DNA sequences and trans-acting protein factors that regulate transcription of the TH gene during hypoxia. The mechanisms by which a reduction in O2 tension is transduced into alter cell function including increased gene expression remain unknown. Unpublished results from our laboratory show that the increased TH gene expression during hypoxia does not require activation of the cAMP-PKA signal transduction pathway. We propose that the increase in intracellular free Ca2+ that occurs as a result of membrane depolarization might play an important role. Preliminary findings from our laboratory show that blockade of the voltage operated Ca2+ channel or chelation of intracellular Ca2+ prevent full activation of the TH gene during hypoxia.
Animals↗
Single-dose and steady-state pharmacokinetics of fosinopril and fosinoprilat in patients with hepatic impairment.
The single-dose and steady-state pharmacokinetics of the angiotensin-converting enzyme (ACE) inhibitor fosinopril and its active diacid, fosinoprilat, were evaluated in 6 healthy volunteers and 12 patients with alcoholic cirrhosis. Fosinopril was administered at a dosage of 10 mg once daily for 14 days. Results in the two groups were similar, with no evidence of accumulation of fosinoprilat in hepatically impaired patients. Mean (+/- SD) maximum observed plasma concentrations of fosinoprilat in the healthy subjects were 112.0 +/- 67.2 ng/mL after the first dose and 144.1 +/- 61.7 ng/mL at steady-state. Corresponding values for the hepatically impaired patients were 111.4 +/- 40.1 ng/mL and 140.2 +/- 50.9 ng/mL. The area under the serum concentration versus time curve for healthy volunteers was 790.7 +/- 431.0 ng.hr/mL after the first dose and 940.3 +/- 400.4 ng.hr/mL at steady-state. Similar values were noted in hepatically impaired patients: 926.0 +/- 293.9 ng.hr/mL and 1,255.4 +/- 434.0 ng.hr/mL for first dose and steady-state, respectively. No statistically significant differences were detected in fosinoprilat pharmacokinetic values between healthy and hepatically impaired subjects. Absence of accumulation can be attributed to the dual route of elimination of fosinoprilat reported in previous studies. Renal excretion of fosinoprilat in hepatically impaired patients prevents increased accumulation. The present findings suggest that the starting dose of fosinopril used in hypertensive patients with normal renal and hepatic function can also be used in patients with hepatic impairment secondary to cirrhosis.
Antihypertensive Agents↗
Transitional cell carcinoma of the renal pelvis or ureter: patterns of failure.
OBJECTIVES: To identify recurrence patterns and possible indications for adjuvant treatment. METHODS: Ninety-four patients with transitional cell carcinoma of the renal pelvis or ureter were reviewed to determine their pattern of failure. Factors including gender and age, tumor stage and grade, and extent of surgical procedure and adjuvant radiation therapy (RT) were analyzed with respect to local and distant recurrence and survival. RESULTS: Seventy-seven patients had resections without residual. On multivariate analysis, grade (P = 0.01) and adjuvant RT (P = 0.02) had significant effects on local control. Metastases were solely dependent on stage (P = 0.0001). Survival was dependent on stage (P = 0.0059) and age (P = 0.036), with the use of adjuvant RT of borderline significance (P = 0.07). Twenty-seven patients were excluded from local failure and survival analysis; of these, 3 died within 1 month of surgery, 5 had metastasis at presentation, and 19 had local disease that was unresectable. Eleven of these 19 were treated by RT, resulting in 2 long-term disease-free survivors after receiving doses of 45 and 50.4 Gy. CONCLUSIONS: In patients with adverse factors, such as high grade or stage, close margins, or positive nodes, local control can be improved with adjuvant radiation. Improvement in survival is of borderline significance on multivariate analysis, with approximately 50% of high stage or grade patients developing metastasis.
Adult↗
The diagnosis of toxoplasmosis using IgG avidity.
Current methods to establish the duration of toxoplasma infection in pregnant women and for the diagnosis of toxoplasmosis in the neonate or HIV infected patient have significant limitations. We assessed the precision of a commercial ELISA for the detection of toxoplasma specific IgG and adapted the assay to measure avidity using an elution agent washing step. The sensitivity and specificity of the ELISA were 100 and 75% respectively and optimal measurement of avidity was achieved using 6 M urea as the elution agent. Toxoplasma lymphadenopathy of less than 3 months duration was associated with low avidity specific IgG but some discordant findings were recorded. Serial measurement of IgG avidity assisted the distinction between actively produced antibody in infants with congenital toxoplasmosis and passively acquired antibody of maternal origin in uninfected babies. There was no significant difference between avidity levels in HIV infected patients with or without cerebral toxoplasmosis.
AIDS-Related Opportunistic Infections↗
Boerhaave's syndrome complicated by a large bronchopleural fistula.
We report a case Boerhaave's syndrome complicated by a large bronchopleural fistula due to autolysis of lung parenchyma by gastric contents, a complication not previously documented to our knowledge.
Aged↗
Brain cytochrome oxidase activity after kindled seizures: a quantitative histochemical mapping study.
Quantitative histochemistry was used to analyze changes in cytochrome oxidase (CO) activity in 93 brain regions after entorhinal cortex kindling. Rats were kindled to at least six stage-5 seizures and sacrificed either 24 h or 28 days after the last convulsion. Regional brain CO activity was quantitated in histological sections using calibrated densitometric standards. No statistically significant differences in regional CO activity between kindled and control brains were seen either 24 h or 28 days after the last convulsion. These results suggest that the brain changes underlying the kindling state are not reflected in localized alterations in mitochondrial respiratory capacity. They also indicate that long-lasting changes in regional brain CO activity recently found after electroconvulsive shock are not common to all types of seizures.
Animals↗