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R D Smith

Publications and source records attributed to R D Smith.

At least 289 records · Page 16Linked to original sources
PubMed1991

Effects of vehicle supplementation on total estradiol absorption from a transdermal estradiol delivery system.

OBJECTIVE: To evaluate the effects of vehicle supplementation on serum estradiol (E2) delivery pharmacokinetics from the Ciba-Geigy (Summit, NJ) 0.1-mg Estraderm Patch. DESIGN: Postmenopausal women were randomized to a 28-day crossover treatment protocol separated by a 14-day wash out period. SETTING: Normal human volunteers were studied in an academic research environment. PATIENTS, PARTICIPANTS: The subject pool included eight healthy postmenopausal women between 32 and 60 years of age. INTERVENTIONS: In treatment A, a 0.1-mg Estraderm Patch was worn for 7 days; in treatment B, and identical patch was worn into which 0.6 mL of ethanol was injected on day 3 of use. MAIN OUTCOME MEASURES: Serum E2 levels were measured in both groups. RESULTS: Although E2 absorption showed characteristic interpatient variability, addition of ethanol significantly extended the mean time for serum E2 levels to return to baseline, without increasing peak absorption. The mean extension was 50 hours. CONCLUSION: The addition of ethanol to the Estraderm Patch increased the duration of elevated serum E2 levels measured in menopausal women, thus potentially increasing the effective life span of the transdermal therapeutic system.

Absorption↗
PubMed1991

Recruitment of pathology trainees. Recent trends from the 1989 Association of Pathology Chairmen's Survey of first-year pathology residents.

The evolving pathology manpower shortage requires that we examine recruitment issues closely. We present data from the 1989 Association of Pathology Chairmen residents' questionnaire and analyze the most important recruitment patterns. Of 685 first-year pathology residents in 1989, 451 (66%) responded to the survey. When compared with other specialties, 1989 pathology residents are older (mean age, 30.1 years), more frequently women (38%), more often foreign medical graduates (23%), and more commonly have MD/PhD degrees (7.8%). Among pathology residents, the fifth year of required training is the most important negative factor in choosing pathology. Over 50% of 1989 first-year pathology residents changed their mind about another specialty to enter pathology; 37% chose pathology only after graduating from medical school. In 1988 and 1989, 63% of first-year pathology residents responding to the Association of Pathology Chairmen residents' questionnaire indicated that role models were an important factor in their specialty choice. The most typical role model was a male pathologist, approximately 47 to 48 years old. Role model influence tended to be greater for those residents who decided to enter pathology earlier in medical school. Nevertheless, over 50% of those residents who decided to enter pathology after medical school claimed that role model influence was important in their choice. Role models remain a valuable resource for improved recruitment into pathology.

Adult↗
PubMed1991

Long-term treatment of social phobia with clonazepam.

Twenty-six socially phobic outpatients were treated with clonazepam for the relief of symptoms. At evaluation, which took place after an average of 11.3 months of continuous treatment, 22 (84.6%) patients showed good improvement and 4 (14.4%) showed no improvement or were not recovered. The dose declined over time, from a peak mean of 2.1 mg/day to a mean of 0.94 mg/day at follow-up. Side effects are described, along with individual case descriptions that illustrate important aspects of the use of benzodiazepines for the treatment of social phobia.

Adult↗
PubMed1991

Pharmacology of DuP 532, a selective and noncompetitive AT1 receptor antagonist.

DuP 532 (2-propyl-4-pentafluoroethyl-1-[(2'-(1H-tetrazol-5-yl)bip hen yl- 4-yl)methyl]imidazole-5-carboxylic acid) inhibited the specific binding of [125I]angiotensin II (AII) for the subtype receptor AT1 in rat adrenal cortical membranes with an IC50 of 3.1 X 10(-9) M, but not the [125I]AII binding for the subtype AT2 sites in rat adrenal medulla tissues. It inhibited the contractile response to AII selectively and noncompetitively in the isolated rabbit aorta with a KB value of 1.1 X 10(-10) M. The selective AII antagonism was confirmed in the guinea pig ileum and the pithed rat. In conscious rats, DuP 532 inhibited the AII-induced pressor effect, aldosterone secretion, and water drinking induced by AII. In conscious renal hypertensive rats, DuP 532 decreased blood pressure with i.v. and p.o. ED30 of 0.02 and 0.21 mg/kg, respectively. The antihypertensive effect of DuP 532 at 0.3 to 3 mg/kg p.o. lasted for at least 24 hr. In conscious spontaneously hypertensive rats, DuP 532 given i.v. or p.o. at 0.3 to 3 mg/kg reduced blood pressure dose-dependently. DuP 532, at doses up to 100 mg/kg i.v., did not cause a pressor response in conscious normotensive rats, suggesting lack of agonism. DuP 532 exerted selective AII antagonism in conscious dogs. In conscious furosemide-treated dogs, DuP 532 given either at 0.3 and 1 mg/kg i.v. or at 1 to 10 mg/kg p.o. decreased blood pressure. As the AT1 receptors are responsible for AII-induced vasoconstriction, aldosterone secretion, and water drinking, our study indicates that DuP 532 is a potent, orally active, selective, and noncompetitive AT1 receptor antagonist and antihypertensive agent.

Adrenal Cortex↗
PubMed1990

Bicuculline and picrotoxin block phase advances induced by GABA agonists in the circadian rhythm of locomotor activity in the golden hamster by a phaclofen-insensitive mechanism.

Permanent phase shifts in the free-running rhythm of locomotor activity of the golden hamster were induced with microinjections of the gamma-aminobutyric acid (GABA) agonists muscimol or baclofen in the hypothalamic suprachiasmatic nuclei. Muscimol and baclofen exhibit relatively high binding affinities for GABAA and GABAB receptors, respectively. Microinjections of the GABA antagonists, bicuculline methobromide or picrotoxinin, thought to block the actions of GABA at GABAA receptors, could block phase shifts induced by muscimol but not the benzodiazepine, triazolam. Microinjections of the postsynaptic GABAB receptor antagonist phaclofen, which blocks the actions of GABA at postsynaptic but not at presynaptic GABAB receptor sites, did not block the phase-shifting actions of either muscimol or baclofen. GABAergic antagonists when given alone did not induce phase shifts. Collectively, these studies indicate that when activated by exogenous GABAergic agents, a GABAergic system associated with both GABAA and GABAB receptors exists as a neural regulatory mechanism that can reset the mammalian circadian clock. However, GABAergic synaptic pathways may not be normally involved in the circadian timing system.

Animals↗
PubMed1990

Sensitivity considerations for large molecule detection by capillary electrophoresis-electrospray ionization mass spectrometry.

The use of the electrospray ionization (ESI) method for interfacing capillary electrophoresis with mass spectrometry (CE-MS) is particularly well suited for the analysis of large molecules due to the multiple charging phenomenon. While ionization efficiency is very high, the available ion current is dispersed over more peaks so that the maximum peak intensity obtainable declines significantly for large molecules. Sensitivity with ESI can be improved by operation at very low flow-rates, an ideal situation for CE-MS. These and other considerations related to sensitivity are illustrated using ESI-MS measurements for cytochrome c.

Animals↗
PubMed1990

New developments in biochemical mass spectrometry: electrospray ionization.

The principles, development, and recent application of electrospray ionization-mass spectrometry (ESI-MS) to biological compounds are reviewed. ESI-MS methods now allow determination of accurate molecular weights for proteins extending to over 50,000, and in some cases well over 100,000. Similar capabilities are being developed for oligonucleotides. The instrumentation used for ESI-MS is briefly described and it is shown that, although ionization efficiency appears to be uniformly high, detector sensitivity may be directly correlated with molecular weight. The use of tandem mass spectrometry (e.g., MS/MS) for extending collision-induced dissociation (CID) methods to the structural studies of large molecules is described. For example, effective CID of various albumin species (molecular weight approximately 66,000) can be obtained, far larger than obtainable for singly charged molecular ions. The combination of capillary electrophoresis, in both free solution zone electrophoresis and isotachophoresis formats, as well as microcolumn liquid chromatography with ESI-MS, provides the capability for on-line separation and analysis of subpicomole quantities of proteins. These and other new developments related to ESI-MS are illustrated by a range of examples. Fundamental considerations suggest even more impressive developments may be anticipated related to detection sensitivity and methods for obtaining structural information.

Biochemistry↗
PubMed1990

Primary sequence information from intact proteins by electrospray ionization tandem mass spectrometry.

Tandem mass spectrometry has been used to obtain information related to portions of the primary sequence for an intact protein, bovine ribonuclease A. Multiply charged molecular ions, generated by electrospray ionization, were collisionally dissociated at low energies in a triple quadrupole mass spectrometer to yield singly and multiply charged fragment ions that can be assigned to the known sequence of the protein. Dissociation of the highly charged molecular ions resulted in pairs of complementary product ions. The higher order (gas-phase) protein structure affects the dissociation processes, as observed in comparisons of tandem mass spectra of the native and disulfide-reduced forms of ribonuclease A.

Amino Acid Sequence↗
PubMed1990

Effect of reducing disulfide-containing proteins on electrospray ionization mass spectra.

Electrospray ionization produces multiply charged molecular ions for biomolecules with molecular weights in excess of 100,000. This allows mass spectrometers with limited mass-to-charge range to extend their molecular weight range by a factor equal to the number of charges. The maximum number of observed charges for peptides and smaller proteins correlates well with the number of basic amino acid residues (Arg, Lys, His), except for disulfide-containing molecules, such as lysozyme and bovine albumin. However, reduction of disulfide linkages with 1,4-dithiothreitol (Cleland's reagent) may allow the protein to be in an extended conformation and make "buried" basic residues available for protonation to yield higher charged molecular ions by the electrospray ionization process. For larger proteins reduction of disulfide bridges greatly increases the maximum charge state, but charging of basic amino acid residues remains less efficient than for smaller proteins.

Disulfides↗
PubMed1990

Capillary isotachophoresis with UV and tandem mass spectrometric detection for peptides and proteins.

The application of capillary isotachophoresis (CITP) and combined CITP-mass spectrometry (MS) for peptides and proteins is demonstrated. Separation of simple peptide mixtures, as well as enzymatic digets of proteins, is also reported using CITP with UV detection. The potential utility of CITP for proteins is demonstrated. Initial studies of combined CITP-MS of enzymatic digests is also demonstrated, showing the potential for rapid sequence determination.

Amino Acid Sequence↗
PubMed1990

Recruitment of pathology residents: APC questionnaire results, 1987 and 1988.

Our data show a persistent decline of US graduates entering pathology. Moreover, our data indicated that the NRMP provides only a small percentage of the total pathology slots ultimately filled. If the intentions of the 1988 cohort remain consistent, the predictions of Anderson et al concerning a shortage of community-hospital and private-laboratory pathologists seem to be well-founded. This evidence, coupled with the long-acknowledged shortage of academic pathologists, makes improved recruitment an imperative. Recent reports have described several potentially important recruitment tools. However, substantial change in recruitment needs to take place if significant shortages are to be avoided.

Adult↗
PubMed1990

Evaluation of the effect of azapropazone on neutrophil migration in anaesthetized swine using a multichamber blister suction technique.

1. The purpose of this study was to determine the in vivo inhibitory efficacy of azapropazone on neutrophil migration. The effects of azapropazone given at a dose of 100 mg kg-1 i.v. every 2 h on the neutrophil migration into skin inflammation sites (blister fluid) as well as into an autologous serum (+/- chemoattractant) placed above the blister surface (2nd chamber) were determined. 2. Azapropazone treatment schedule maintained blood levels at 70-100 micrograms ml-1 throughout the time course (360 min) of the experiment. 3. Azapropazone significantly inhibited (48 +/- 6%) neutrophil migration into the blister fluid (as evident from the decrease in myeloperoxidase activity). 4. Azapropazone significantly inhibited the neutrophil migration into the autologous serum either with (65 +/- 5%) or (35 +/- 6%) without the chemoattractant, formyl-methionyl-leucyl-phenylalanine (FMLP). The chemoattractant, FMLP, markedly increased neutrophil migration into the autologous serum by approximately 1.5 to 2 times the non-FMLP treated group. Azapropazone was more efficacious in inhibiting the neutrophil migration in the presence of FMLP than in its absence. 5. We conclude that azapropazone is an effective inhibitor of neutrophil migration into topically inflamed sites in anaesthetized swine.

Anesthesia↗
PubMed1990

Evaluation of the effect of azapropazone on neutrophil migration in regional myocardial ischaemia/reperfusion injury in rabbits.

1. The purpose of the present study was to determine the myocardial cytoprotective efficacy of azapropazone (AZA) and its potential site of action on neutrophil infiltration into reperfused/ischaemic myocardium with or without in vivo activation of neutrophils in rabbits. 2. AZA, 100 mg kg-1, was administered i.v. 10 min after occlusion of the left circumflex (LCX) artery in rabbits with and without pretreatment with phorbol myristate acetate ester (PMA). The LCX occlusion was then released at 10 min after AZA administration. Haemodynamic parameters (heart rate, LV pressure, mean arterial blood pressure and dp/dt) were monitored throughout the experiment. After 60 min reperfusion, the area at risk was delineated and the heart was then excised and divided into epi- and endocardial pieces for analysis of myeloperoxidase activity. 3. AZA inhibited neutrophil infiltration into the reperfused/ischaemic rabbit myocardium with and without PMA treatment. The inhibition of neutrophil infiltration was more apparent in the epicardium than in the endocardium. Additionally, AZA inhibited to a similar extent the in vivo PMA-stimulated neutrophil migration into the epicardium and endocardium area at risk. AZA had no significant effect on the haemodynamic parameters as compared to control. 4. AZA administered in an anaesthetized rabbit model of LCX occlusion/reperfusion resulted in the reduction of infarct size. 5. It is concluded that AZA has significant inhibitory effects on neutrophil migration which might contribute to its myocardial cytoprotective effect.

Animals↗
PubMed1990

Cervical myelography: survey of modes of practice and major complications.

A total of 68 major complications of cervical myelography were reported by 220 neuroradiologists in a mail survey. Two-thirds of the complications were attributed to cervical spine hyperextension and one-third to lateral C1-2 puncture. Narrow sagittal diameter of the spinal canal and severe cervical spondylosis were frequent contributing factors to hyperextension injury of the cervical spinal cord. Clinical and radiographic premyelography screening is suggested, with magnetic resonance imaging performed first in patients with spinal canal stenosis, severe spondylosis, and/or myelopathy of any cause. Neck extension should be minimal during myelography. All C1-2 punctures should be monitored with lateral fluoroscopy for accurate needle positioning and prevention of contrast medium injection into the spinal cord.

Cervical Vertebrae↗
PubMed1990

Long-term renal effects of enalapril therapy in patients with renal insufficiency.

Angiotensin-converting enzyme inhibitory therapy is widely used to treat hypertension. With long-term use, it is now being shown to have a beneficial effect on renal function and proteinuria in patients with renal insufficiency. When hypertensive patients with renal insufficiency are treated with enalapril, glomerular filtration rate is maintained, effective renal plasma flow is increased, and microalbuminuria and gross proteinuria are reduced. These beneficial renal changes with enalapril therapy differ from those of most other conventional antihypertensive medications. Clinical awareness of potential problems with hyperkalemia and increasing azotemia, particularly in the setting of salt/volume depletion, is important to assure optimal patient management. When these problems occur, they are nearly always reversible by correcting salt/volume status and/or interrupting enalapril therapy.

Aged↗
PubMed1990

Enalapril improved renal function and proteinuria in chronic glomerulopathies.

Ten patients (6 men, 4 women, age range 35-64 years) with glomerulopathies were studied. Diagnoses were membranoproliferative glomerulonephritis (GN; n = 4), membranous GN (n = 3), focal and diffuse glomerulosclerosis (n = 2), and poststreptococcal GN (n = 1). These were confirmed by renal biopsy in 8 of the 10 patients. All patients had reduced function (creatinine clearance 15-55 ml/min); proteinuria ranged from 1.0 to 10.4 g/day. Three normotensive patients received enalapril 10 mg once daily. Seven hypertensives received enalapril 10-40 mg once daily to control blood pressure (BP). Concomitant diuretic therapy (furosemide/bumetanide) was administered to 6 patients. There were visits every 14 days for a mean of 15.9 months (range 9-26 months). Diet was monitored, and BP was significantly controlled in the hypertensive patients but not altered in the normotensives. Serum creatinine, blood urea nitrogen, creatinine clearance, and 24-hour urinary protein improved and did not deteriorate progressively. Serum potassium did not change significantly. No adverse clinical events were noted. Enalapril therapy may improve the prognosis for GN over time by maintaining glomerular filtration rate and decreasing proteinuria.

Adult↗