Application of Innovative Subject Recruitment System for Batch Enrollment: A Pilot Study

INTRODUCTION

Using a digital process that leverages electronic health records (EHRs) can ease many of the challenges presented by the traditional enrollment process for clinical trials. We tested if automated batch enrollment using a technology-enabled subject recruitment system (TESRS) enhances recruitment while preserving representation of research subjects for the study population in our study setting.

METHODS

An ongoing community-based prospective adult cohort study was used to randomize 600 subjects who were eligible by age and residential address to TESRS (n = 300) and standard mailing method (n = 300), respectively, for 3 months. Then, TESRS was initiated and included automatic identification of patients' preference for being contacted (online patient portal vs postal mail) from EHRs and automatic sending out of invitation letters followed by completion of a short online survey for checking eligibility and the digital consent process if eligible. We compared (1) median time to consent from invitation sent out per subject and total subjects recruited after a 3-month recruitment period, (2) the estimated study staff's time, and (3) representation of sociodemographic characteristics (e.g., age, sex, race, SES measured by HOUSES index, and rural residence) between subjects recruited via TESRS and those via traditional mailing methods.

RESULTS

Median age of randomized subjects (n = 600) was 63 years with 52.0% female and 89.2% non-Hispanic White. Over a 3-month period, results showed consent rate via TESRS was 13% (39/297) similar to 11% (31/295) via standard mailing. However, recruitment was significantly faster with the TESRS approach (median 7 vs 26 days) given the study staff's effort. Study staff's time saved by using TESRS compared to standard mailing approach was estimated at 40 min per subject (equivalent to 200 h for 300 subjects). No significant differences in characteristics of research subjects from the study population were found.

CONCLUSION

Our study demonstrated the utility of TESRS as a subject recruitment digital technology which significantly enhanced the recruitment effort while reducing the study staff burden of recruitment while maintaining the consistency of characteristics of recruited subjects. The strategy and support for implementing and testing TESRS in other study settings should be considered.

Successful treatment of Rhizopus arrhizus rhino-orbital-cerebral mucormycosis with isavuconazole salvage therapy following extensive debridement

A 61-year old lady with poorly-controlled type 2 diabetes mellitus was diagnosed with rhino-orbital-cerebral mucormycosis following presentation with sinusitis, ophthalmoplegia, proptosis and facial numbness. She was treated successfully with aggressive surgical intervention including orbital exenteration, accompanied by anti-fungal therapy with liposomal amphotericin B and posaconazole, followed by isavuconazole as salvage therapy. We discuss the challenges around optimising antifungal therapy of this lethal infection in the context of hepatic and renal toxicity.

Circadian response of annual weeds in a natural setting to high and low application rates of four herbicides with different modes of actions

Four herbicides [glyphosate (GLYT), an amino acid synthesis inhibitor; glufosinate (GLUF), a glutamine synthetase inhibitor; fomesafen (FOME), a protoporphyrinogen oxidase inhibitor, and chlorimuron ethyl (CLIM), an acetolactate synthase inhibitor] were used to examine the influence of time of day of application on the control of a variety of annual broadleaf weeds in field studies conducted in Minnesota (five studies on GLYT and GLUF, three studies on FOME and CLIM). All herbicides were applied with an adjuvant at recommended high and low (half or quarter strength) rates every 3h between 06:00 and 24:00h local time. Visual ratings of percent weed control evaluated at 14d were analyzed by herbicide and application rate for each study and across studies for time-of-day effect by analysis of variance (ANOVA) and single cosinor. A circadian response to each herbicide was found, with greatest weed control observed between 09:00 and 18:00h. Increasing the herbicide application rate did not overcome the time-of-day effect (ANOVA: p < or = 0.008 for time-of-day effect for each herbicide and application rate). The least-squares fit of a 24h cosine was significant (p < or = 0.001) for each herbicide and application rate, with double amplitudes of 18-82% (units = % visual control) and estimated peaks (acrophases) near midday between 12:40 and 13:35h. Analysis of residuals obtained from multiple regression that included weed height, herbicide rate, temperature, and relative humidity as independent factors also found a significant time-effect by both ANOVA and cosinor for each herbicide and rate, with acrophases advancing significantly by 3 to 7h for GLYT and GLUF, but not for FOME or CLIM. These results suggest that the four herbicides, while belonging to different families with different modes of action, may reveal different peak times of efficacy when adjusting for environmental factors. Nonetheless, each displays similar circadian patterns when influenced by these factors under natural seasonal field conditions. The within-day rhythmic differences found in weed control are large enough to warrant consideration of the practical financial and environmental importance of the time-of-day that these and other herbicides are applied.

Anterior submucous laryngeal cleft

Upper airway obstruction in the newborn is frequently due to congenital laryngeal anomalies. One of these, the posterior laryngeal cleft, is often associated with subglottic stenosis and respiratory difficulty. This discussion of the anterior laryngeal cleft reports findings in an infant who required intubation immediately after birth and survived only 3 days. The anterior cricoid cleft was associated with severe congenital anomalies including congenital tracheal stenosis.

Mucoepidermoid carcinoma of the trachea in a child

Primary tracheal neoplasms in children, especially malignant lesions, are extremely rare. We report a unique case of low-grade mucoepidermoid carcinoma of the trachea in a 4-year old child, presenting as new-onset asthma. Using the ventilating resectoscope, endoscopic excision was accomplished without complications. The case is presented with documentation including airway films, endoscopic photographs, and histopathology. The diagnosis of tracheal masses depends upon maintaining a high index of suspicion, complemented by imaging and timely diagnostic endoscopy. A review of the literature is included.

Treatment of penicillin-resistant pneumococcus with penicillin: a case report

Antibiotic resistance of Streptococcus pneumoniae is on the rise in many parts of the world, and varies widely across the United States. This is of growing concern as organisms become resistant to cephalosporins and macrolides as well as to beta-lactam antibiotics. Susceptibility testing has become a critical element in antibiotic selection. In vitro susceptibility, however, may not correlate with clinical susceptibility. For example, penicillin G in appropriate doses is often effective therapy for drug-resistant Streptococcus pneumoniae pneumonia. This report takes into account in vitro susceptibility as well as the patient's coexisting morbidities in the treatment of penicillin-resistant S pneumoniae with penicillin G.

Biliary-shunt fistula following transjugular intrahepatic portosystemic shunt placement

Sepsis following the placement of a transjugular intrahepatic portosystemic shunt (TIPS) has been reported in up to 10% of cases. This report describes an unusual case of polymicrobial gram-negative sepsis after placement of TIPS associated with a cholangiographically documented fistulous connection between the biliary tree and shunt. The patient was treated with temporary biliary stent placement, endoscopic sphincterotomy, and broad-spectrum antibiotics with rapid closure of the fistula and resolution of sepsis. In the absence of hemobilia, it is hypothesized that flow through the fistula allowed bilious contamination of the systemic circulation and subsequent inoculation with enteric flora. The prevalence of biliary-vascular fistula after placement of TIPS is unknown. It may be a previously unsuspected source of sepsis after placement of TIPS and is likely to be overlooked unless endoscopic retrograde cholangiopancreatography is performed.

Surface and bulk absorption characteristics of chemically vapor-deposited zinc selenide in the infrared

<p>Chemically vapor-deposited zinc selenide exhibits outstanding properties in the infrared and has been established as a prime material for transmissive optics applications. Here we present and discuss data relating to the surface and the bulk absorption forward-looking infrared- (FLIR-) grade chemically vapor-deposited ZnSe, at wavelengths (2-20 µm) and temperatures (100-500 K) of current interest.</p><p>This investigation is based on both spectral emittance measurements and infrared transmission spectroscopy performed in the context of a systems development program. Surface effects can be detected at wavelengths of up to 14 µm and usually predominate at wavelengths of less than 8 µm. Fractional surface absorptions are temperature independent from approximately 200 to 400 K and can be fitted to a Fourier series, at wavelengths ranging from 3.5 to 13.5 µm. The bulk absorption coefficient (βv) is strongly dependent on temperature as well as wavelength, but it can be approximated by a bivariate polynomial expressin that yields recommended values. At wavelengths λ ≲ 10 µm, βv decreases with increasing temperature; it is shown that a wavelength-independent Debye-Waller factor provides a correct description of the temperature dependence, thus pointing to infrared-active localized modes. At wavelengths λ ≳ 14 µm, βv increases with temperature and exhibits temperature dependencies (T(1.7), T(2.6)) that reflect three- and four-phonon summation processes. Finally, an analysis of the temperature dependence of βv at 10.6 µm demonstrates that the intrinsic lattice dynamical contribution to bulk absorption at this wavelength should be close to 4 × 10(-4) cm(-1), in accord with the results of earlier laser calorimetry tests performed on exceptionally pure laser-grade chemically vapor-deposited ZnSe.</p>

Anatomical and morphological evaluation of pacemaker lead compression

In recent years, pacemaker lead failure due to compressive damage has been reported with increasing frequency. To document the mechanism of this failure, we evaluated explanted mechanically damaged leads with electrical testing, optical microscopy, and in some cases, scanning electron microscopy (SEM). In addition, we performed an autopsy study to measure the compressive loads on catheters placed percutaneously through the costoclavicular angle, as well as by cephalic cutdown. Of the 49 explanted compression damaged leads with enough clinical data for analysis, all had been placed by percutaneous subclavian puncture. Our autopsy data confirmed the significant increase in pressures generated in the costoclavicular angle for medial percutaneous subclavian catheterization (126 +/- 26 mmHg) compared to a more lateral percutaneous subclavian puncture (63 +/- 15 mmHg) or a cephalic cutdown (38 +/- 13 mmHg) (P < 0.01). In vivo coil compression testing documented loads up to 100 pounds per linear inch of coil and a compressive morphology by SEM identical to that seen in the clinical explants. Pacemaker leads appear to be susceptible to compression damage when placed by subclavian venipuncture. When possible, leads should be placed such that they avoid the tight costoclavicular angle.

Computerization of the Medical Quality Improvement program at a chronic care hospital

Utilizing micro computer technology and a relational data base manager we have successfully computerized the Peer Review functions of the Medical Quality Improvement program at Monroe Community Hospital, a Chronic Care Hospital. The developed computer programs enhance patient care by focusing on potential practitioner errors. The programs allow for trend analysis and identify the disciplines to whom problems have been referred. This effort has pointed to the need of a standardized lexicon to describe and catalogue potential practitioner errors.

Bilateral choanal atresia associated with malformation of the anterior skull base: embryogenesis and clinical implications

A number of craniofacial and systemic malformations have been described in association with choanal atresia. We report a case of bilateral choanal atresia associated with congenital absence of the cribriform plate, crista galli, and perpendicular plate of the ethmoid bone. The anterior skull base defect was detected by using high-resolution computed tomography with three-dimensional reconstructions. The findings support the mesodermal flow theory of choanal atresia, in which there is excess migration of neural crest cells into the developing nasal septum and posterior choanae. This occurs at the expense of cells that would otherwise form the rest of the ethmoid complex. Clinical implications include the need for adequate preoperative imaging of the anterior skull base and consideration of potential intracranial complications during surgical repair.

Incidence of perforation with Goode T-tube

Two groups of patients from the same era were retrospectively studied in Cincinnati and Chicago. In Cincinnati two subgroups were studied. The first group received myringotomy with insertion of a 'T'-shaped ventilating tube (75 patients, 140 ears, 147 insertions). Fifty-eight ears still had the tube in place, 31 had healed after spontaneous extrusion, 17 had healed after removal of the tube, 20 had persistent perforation after the tube was gone, 2 had a cholesteatoma, and 4 patients (7 ears) were lost to follow-up. The second set received myringotomy and insertion of a small grommet (Donaldson tube, 71 patients, 140 ears, 164 insertions) tympanostomy tube. None could be documented to still have the tube in place, 156 ears healed after spontaneous extrusion, none required removal, 3 ears had a persistent perforation after the tube was gone, none had cholesteatoma, and 5 patients (5 ears) were lost to follow-up. The perforation rate for the T-tube is 13.6% and for the grommet is 1.8% (P = 0.0005). In Chicago, 93 patients who received the Goode T style tube (175 ears, 175 insertions) prior to March, 1986 were evaluated. The degree of retraction of the tympanic membrane preoperatively was recorded. No ears still had the tube in place, 145 had healed after spontaneous extrusion or removal of the tube, 30 had persistent perforation 12 months after the tube was gone, 4 had a cholesteatoma, and 8 patients (15 ears) were lost to follow-up. The rate of perforation is 18.8% which is not statistically different from the Cincinnati rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal secretion and hepatic clearance of human multiple renin forms

Human active renin can be separated into at least five forms by isoelectric focusing. The present study assessed the preferential renal secretion and hepatic degradation of renin forms in humans. The renin form profile of secreted renal renin was determined before transplant in an ex vivo kidney donor perfusion system and compared with the peripheral plasma multiple renin form profile of normal subjects. The effect of hepatic degradation on renin forms was assessed in hepatic vein plasma in comparison with infrarenal vena cava plasma in hypertensive patients during renal vein renin studies. The results revealed a significantly greater proportion of the more basic forms in the perfusate of donor kidneys compared with normal plasma. In hypertensive patients the proportion of the more basic renin forms in the hepatic vein was significantly decreased in comparison with the infrarenal vena cava. Thus, the human kidney may preferentially secrete the more basic renin forms. In contrast, the liver preferentially degrades the more basic forms, giving these forms a shorter plasma half-life. The preferential secretion and clearance of the more basic forms of renin may contribute to short-term control of human renin-angiotensin system activity.

Uptake and distribution of lidocaine in fetal lambs

The fetal uptake of lidocaine was measured continually and quantitatively during and after a constant rate intravenous (iv) maternal infusion into five chronically prepared pregnant ewes. Lidocaine, 6 mg/kg (base), was infused at a constant rate for 1 h and measurements continued to 5 h. Rate of fetal uptake was determined from the product of the umbilical venous (UV) and fetal aortic (FA) concentration difference and umbilical blood flow (Qu). Total fetal uptake was determined by integrating fetal uptake rate with respect to time. Maternal and fetal protein binding was determined, and its effect on fetal blood concentrations was evaluated. Mean total fetal uptake as it related to time and infused dose increased linearly (r = 0.998, P less than 0.001) with a constant, weight-normalized fetal-maternal dose fraction of 0.45 during the infusion. Despite rapidly declining blood concentrations after the infusion, uptake increased an additional 17%. The sevenfold variation in uptake appeared to be inversely related to the biodegradation rate of lidocaine. Fetal-maternal concentration ratios (F/M) increased during declining blood concentrations. Protein binding determinations for maternal and fetal blood were 43.6 +/- 2.48% and 26.9 +/- 1.59%, respectively. These values were used to calculate the F/M in conjunction with the maternal and fetal pH. At maternal-fetal equilibrium the calculated F/M, 1.0 +/- 0.05, closely approximated the observed, 1.0 +/- 0.03. Variations in lidocaine concentrations among the vital organs 4 h after the infusion were small, but high concentrations of metabolites were found in the lungs and kidneys. The results challenge the validity of placental transfer estimates commonly based on the F/M and umbilical cord blood concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta subunit of (Na+ + K+)-ATPase contains three disulfide bonds

Previous studies of titratable (Na+ + K+)-ATPase sulfhydryl groups have indicated the presence of one disulfide bond per mole of holoenzyme. This single disulfide cross-link was assigned to the beta subunit on the basis of the difference between the number of titrated "free" sulfhydryl groups and the total number of titrated sulfhydryl groups for each subunit [Esmann, M. (1982) Biochim. Biophys. Acta 688, 251; Kawamura, M., & Nagano, K. (1984) Biochim. Biophys. Acta 694, 27]. In the present study, beta-subunit tryptic peptides containing disulfide cross-links were identified and purified by HPLC. Two new peptides were generated from each disulfide-bonded peptide by reduction with dithiothreitol, and the amino acid compositions of these reduced peptides were determined. The data demonstrate that there are three disulfide bonds in the native beta subunit: 125Cys-148Cys, 158Cys-174Cys, and 212Cys-275Cys. The number of disulfide bonds in the beta subunit was also estimated by titration of sulfhydryl groups with [14C]iodoacetamide. Six sulfhydryl groups were identified: two sulfhydryl groups were titrated without prior reduction, and four were identified only after reduction of the protein with dithiothreitol. These data, suggesting that the beta subunit contains two disulfide bonds, are inconsistent with the peptide isolation experiments, which directly identified three disulfide bonds in the beta subunit. This inconsistency was resolved by demonstrating that approximately 20% of each disulfide bond in the beta subunit was reduced prior to the start of the experiment, resulting in an underestimation of the number of disulfide-bonded sulfhydryl groups in the beta subunit from the titration experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Update of the Cincinnati experience in pediatric laryngotracheal reconstruction

Surgical endeavors in the field of laryngotracheal reconstruction in children have received much interest in the past 15 years. A unique experience with laryngotracheal reconstruction in 203 children is reviewed. The majority (194) of the cases were classified as acquired; only nine were classified as congenital. Excluded from the study were those cases of stenoses managed endoscopically, all resections and end-to-end anastomoses, all anterior cricoid split procedures, and all cases of anterior glottic stenosis repaired by a laryngeal keel. The degree of stenosis was graded into four categories. Five different methods of laryngotracheal reconstruction were used depending on the pathologic lesion in the larynx and trachea. Of the 203 children, 186 (92%) were decannulated. The results support the use of laryngotracheal reconstruction in children with grades 2, 3, and 4 laryngeal stenosis.

The influence of assay variability on pharmacokinetic parameter estimation

The impact of assay variability on pharmacokinetic modeling was investigated. Simulated replications (150) of three "individuals" resulted in 450 data sets. A one-compartment model with first-order absorption was simulated. Random assay errors of 10, 20, or 30% were introduced and the ratio of absorption rate (Ka) to elimination rate (Ke) constants was 2, 10, or 20. The analyst was blinded as to the rate constants chosen for the simulations. Parameter estimates from the sequential method (Ke estimated with log-linear regression followed by estimation of Ka) and nonlinear regression with various weighting schemes were compared. NONMEM was run on the 9 data sets as well. Assay error caused a sizable number of curves to have apparent multicompartmental distribution or complex absorption kinetic characteristics. Routinely tabulated parameters (maximum concentration, area under the curve, and, to a lesser extent, mean residence time) were consistently overestimated as assay error increased. When Ka/Ke = 2, all methods except NONMEM underestimated Ke, overestimated Ka, and overestimated apparent volume of distribution. These significant biases increased with the magnitude of assay error. With improper weighting, nonlinear regression significantly overestimated Ke when Ka/Ke = 20. In general, however, the sequential approach was most biased and least precise. Although no interindividual variability was included in the simulations, estimation error caused large standard deviations to be associated with derived parameters, which would be interpreted as interindividual error in a nonsimulation environment. NONMEM, however, acceptably estimated all parameters and variabilities. Routinely applied pharmacokinetic estimation methods do not consistently provide unbiased answers. In the specific case of extended-release drug formulations, there is clearly a possibility that certain estimation methods yield Ka and relative bioavailability estimates that would be imprecise and biased.

AAQUANT: a computer program for quantitative amino acid analysis of proteins and peptides

Quantitative amino acid analysis is an important tool used in the characterization and structural determination of peptides and proteins. A new computer program, AAQUANT, has been developed specifically to aid researchers in analyzing amino acid composition data. AAQUANT calculates amino acid recoveries, including 95% confidence intervals, following acid hydrolysis of peptides and proteins, and also includes useful routines to locate regions of a specified amino acid composition in known protein sequences, compute amino acid composition reports of known protein sequences, generate proteolytic digestion maps of proteins, and create and edit protein sequence data files. This report describes the AAQUANT routines, and demonstrates the use of the program.

Airway reconstruction following laryngotracheal thermal trauma

Care of burn patients is a complex problem for the trauma team involving management of fluid and electrolyte imbalances, infections, and ultimately reconstruction. Patients with burns of the head, neck, and upper thorax present a series of unique problems because of a high incidence of associated upper and lower airway thermal trauma necessitating intubation and ventilatory support. A series of cases requiring laryngotracheal reconstruction following severe burns to the head and neck region is reported. Methods of treatment are discussed as well as modifications of standard burn therapy to decrease the incidence of severe scarring.

All three potential N-glycosylation sites of the dog kidney (Na+ + K+)-ATPase beta-subunit contain oligosaccharide

The beta-subunit of dog kidney (Na+ + K+)-ATPase is a sialoglycoprotein and contains three potential N-glycosylation sites. In this study, the oligosaccharide chains of purified dog kidney beta-subunit were labeled with tritium by oxidation with sodium periodate or galactose oxidase followed by NaB3H4 reduction. The beta-subunit was extensively digested by trypsin and the radioactive peptides were purified by HPLC. The enzyme, glycopeptidase A, which catalyzes the removal of N-linked oligosaccharide chains and the conversion of the glycosylated Asn residue to Asp, was used to demonstrate that a number of purified beta-subunit tryptic peptides were glycosylated. Amino-acid analysis of these beta-subunit peptides following glycopeptidase-A treatment revealed the expected Asn to Asp conversion for Asn-157, Asn-192 and Asn-264, demonstrating that all three potential N-glycosylation sites of the dog kidney beta-subunit are glycosylated. In addition, amino-acid sequence data suggest that a disulfide bond exists between Cys-158 and Cys-174.

Percutaneous nephrostomy: assessment of renal damage associated with semi-rigid (24F) and balloon (36F) dilation

In an effort to discern the amount of renal damage incurred by antegrade percutaneous nephrostomy and nephrostomy tract dilation, we studied the long-term effect of acutely created 24F and 36F percutaneous nephrostomy tracts on 12 pig kidneys. Half of the nephrostomy tracts were dilated using a semi-rigid 24F fascial dilating system (Amplatz design) and half were dilated using a 36F balloon dilation system. Animals were killed at six weeks and the nephrostomy tract was dissected, fixed in formalin, and microscopic cross-sections were stained with Masson's trichrome stain for collagen prior to morphometry using computerized planimetry. In this study, renal damage from the nephrostomy tract averaged 0.15% of the total renal cortical surface. Balloon dilation to 36F incurred no more significant damage than fascial dilation to 24F.

Molecular cloning and sequence analysis of the (Na+ + K+)-ATPase beta subunit from dog kidney

cDNA complementary to mRNA coding for the beta subunit of dog renal (Na+ + K+)-ATPase has been cloned into lambda gt11 and the nucleotide sequence of the DNA has been determined. The amino acid sequence of the beta subunit polypeptide has also been deduced from the DNA. The mature form of the dog kidney beta subunit contains 302 amino acids with three potential asparagine-linked attachment sites for carbohydrate. The initiation methionine is removed during processing of the polypeptide to its mature form. Although the beta subunit is an integral membrane protein there is no signal sequence for the polypeptide, and hydropathy analysis predicts that the beta subunit polypeptide spans the cell membrane only once. Secondary structure predictions and a model for the structure of the beta subunit are proposed. DNA sequencing of the 5' non-coding region of the mRNA revealed a 200 bp inverted repeat from the coding region. Blot hybridization of a fragment of the beta subunit cDNA identified a single mRNA species of 2.7 kb in dog kidney and several rat tissues. RNA from rat liver was deficient in mRNA that hybridized to the dog kidney beta subunit cDNA, although mRNA that hybridized to an alpha subunit cDNA was detected. RNA from a human hepatoma cell line, HepG2, however, contained comparable levels of mRNA for both the alpha and the beta subunits.

Orientation of the beta subunit polypeptide of (Na+ + K+)ATPase in the cell membrane

Although the animal cell (Na+ + K+)-ATPase is composed of two polypeptide subunits, alpha and beta, very little is known about the beta subunit. In order to obtain information about the structure of this polypeptide, the beta subunit has been investigated using proteolytic fragmentation, chemical modification of carbohydrate residues, and immunoblot analysis. The sialic acid moieties on the oligosaccharide groups on the beta subunit of (Na+ + K+)-ATPase were labeled with NaB3H4 after oxidation by sodium periodate, or the penultimate galactose residues on the oligosaccharides were similarly labeled after removal of sialic acid with neuraminidase and oxidation by galactose oxidase. All of the carbohydrate residues of the protein are located on regions of the beta subunit that are found on the non-cytoplasmic surface of the membrane. Cleavage of the galactose oxidase-treated, NaB3H4-labeled beta subunit by chymotrypsin at an extracellular site produced labeled fragments of 40 and 18 kDa, indicating multiple glycosylation sites along the polypeptide. Neither the 40 kDa fragment nor the 18 kDa fragment was released from the membrane by chymotrypsin digestion alone, but after cleavage the 40 kDa fragment could be removed from the membrane by treatment with 0.1 M NaOH. This indicates that the 40 kDa fragment does not span the lipid bilayer. The 40 kDa fragment and the 18 kDa fragment are also linked by at least one disulfide bond. The 18 kDa fragment also contains all of the binding sites found on the (Na+ + K+)-ATPase for anti-beta subunit antibodies. Both the 40 kDa fragment and the 18 kDa fragment were also generated using papain or trypsin to cleave the beta subunit. These data indicate that the beta subunit of (Na+ + K+)-ATPase contains multiple sites of glycosylation, that it inserts into the cell membrane near only one end of the polypeptide, and that one region of the polypeptide is particularly sensitive to proteolytic cleavage relative to the rest of the polypeptide.

Uptake and distribution of bupivacaine in fetal lambs

Direct continual measurement of placental drug transfer was introduced to evaluate more precisely the fetal uptake of a commonly used local anesthetic in obstetrics. Bupivacaine, 2.7 mg X kg-1 (base), was infused at a constant rate over 1 h into a maternal jugular vein of five chronically prepared pregnant ewes. Blood was sampled simultaneously from the umbilical vein (UV), fetal aorta (FA), and a maternal artery (MA). Fetal uptake rate was determined from the product of the bupivacaine UV-FA blood concentration difference and the umbilical flow rate (Qu). Total fetal accumulation was determined by integrating uptake rate over 5 h. Correlation of total fetal uptake and the infused mean maternal dose (r = 0.993, P less than 0.001) indicated that during the infusion, mean fetal uptake was a constant fraction (0.16) of the maternal infused dose. Total fetal uptake was linear despite wide individual changes in Qu, suggesting that within limits fetal accumulation is not Qu-dependent. Mean ovine protein binding of bupivacaine by maternal and fetal whole blood was 85.49% +/- 2.61 (SD) and by fetal blood, 40.43% +/- 9.60 (SD). Back-transfer of bupivacaine to the mother proceeded against a higher total bupivacaine concentration because unbound unionized drug concentrations in maternal blood were less than in fetal blood. At maternal-fetal equilibrium when UV and FA total blood concentrations were equal, the calculated fetal/maternal concentration ratio (f/m) (0.36) determined from the maternal and fetal protein binding and pH closely approximated the observed (0.35). The f/m increased during both fetal uptake and back-transfer and cannot be considered a good index of placental transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous removal of renal and ureteral calculi: experience with 400 cases

Percutaneous removal of renal and ureteral calculi was performed in 500 patients since 1979. Experience with our first 100 cases enabled us to accumulate a variety of techniques. We report our experience with the subsequent 400 cases. As judged by plain films of the kidneys, ureters and bladder, and renal tomograms without contrast medium we attained a status free of stones in 99 per cent of the patients with renal and 94.5 per cent with ureteral calculi. Intravenous-assisted local anesthesia was used in 94 per cent of the cases. There was no mortality and the incidence of complications was low. Most patients with renal and ureteral calculi can be managed successfully and safely by percutaneous methods with good patient tolerance and minimal convalescence.

Percutaneous removal of caliceal and other "inaccessible" stones: instruments and techniques

Percutaneous removal of renal stones is becoming an established procedure, especially for stones lying free in the renal pelvis. However, some renal stones, particularly caliceal stones, are less accessible and require special techniques for removal. We discuss these techniques, which include 1) retrograde pyelography to facilitate a thorough understanding of caliceal anatomy and stone position in 3 dimensions, 2) approaches for accurate placement of a nephrostomy tract for straight-line access to the stone(s), 3) judicious use of percutaneous punctures above the 12th rib and secondary percutaneous tracts, and 4) skilled choice and use of a large variety of cutting, extracting and disintegrating instruments with endoscopic and/or fluoroscopic control. The flexible nephroscope is valuable especially to reach inaccessible areas, although its skilled use requires experience. Flexible endoscopy often is aided by pressure irrigation, an assistant and simultaneous fluoroscopic control.

Pursuit of the renal mass. Is ultrasound enough?

The accuracy of ultrasonography in evaluating renal masses was assessed retrospectively in 260 renal lesions detected by intravenous urography in 242 patients. The ultrasonographic diagnosis was confirmed by cyst puncture, surgery, or autopsy. Of the lesions, 168 were benign cysts, and all were diagnosed correctly by ultrasonography. The remaining 92 lesions were renal carcinomas, and 90 were diagnosed correctly by ultrasonography. In retrospect, it was clear that the two missed cancers did not fulfill all the ultrasonographic criteria for a cyst. An algorithm is presented for the differential diagnosis of renal masses primarily by ultrasonography, and the arguments in favor of operative diagnosis of renal masses are rebutted. With the approach described, invasive studies such as cyst puncture and arteriography will be required for a definitive diagnosis in fewer than 10 percent of patients, and the morbidity and expense of the diagnostic approach will be minimized, with no decrease in accuracy.

Renal vascular complications associated with the percutaneous removal of renal calculi

Significant immediate and delayed vascular complications occurred in 4 of 140 patients (3 per cent) undergoing percutaneous removal of renal and ureteral calculi. An understanding of renovascular anatomy, use of a safety guide wire and intraoperative availability of an angiographic balloon catheter may help to prevent and to treat bleeding problems.

Percutaneous nephrolithotomy: extraction of renal and ureteral calculi from 100 patients

A percutaneous nephrostomy tract was used as a conduit to the kidney and ureter for extraction of 149 calculi in 100 patients. A variety of grasping and fragmentation techniques under fluoroscopic and endoscopic control were used to extract calculi in 88 per cent of the patients. With experience, operator efficiency and rate of stone extraction increased from 76 per cent early in the series to 91 per cent in the most recent patients, and the incidence of complications decreased from 17 to 5 per cent. Percutaneous removal of upper tract urinary calculi appears to be an appropriate alternative to an open operation in most patients with symptomatic urolithiasis.

Percutaneous nephrolithotomy. An approach to branched and staghorn renal calculi

Using electrohydraulic lithotripsy, we removed branched or staghorn calculi from four patients via a percutaneous nephrostomy tract with local anesthesia. There were no serious complications, and the patients were able to resume their preadmission activities immediately after discharge from the hospital. Our experience suggests that, eventually, all upper urinary tract calculi may be treatable by a percutaneous approach.

Rapid balloon dilatation of the nephrostomy track for nephrostolithotomy

The Olbert balloon catheter can be used to dilate a nephrostomy track from 9 to 30 F (3 to 10 mm) in a single step. Percutaneous nephrostomy, track dilatation, and percutaneous stone extraction can be performed within 40 to 90 minutes. The authors have used this catheter successfully in 10 patients without encountering complications.

Percutaneous nephrolithotomy with Mazzariello-Caprini forceps

Mazzariello-Caprini forceps were used percutaneously to remove a stone that was impacted distal to the ureteropelvic junction in a patient who had undergone several previous open pyelolithotomies. These forceps open by a rotational rather than a scissoring movement so the shaft size does not increase and they are well suited for operation through a narrow nephrostomy tract. The original design has been modified to allow passage over an angiographic guide wire, thereby placing the forceps precisely at the site of the stone. Also, with the angiographic guide wire to direct them the forceps can be used in a freshly established nephrostomy tract as well as in a mature tract. In our experience the Mazzariello-Caprini forceps have been most useful for nonoperative manipulation of renal and upper ureteral calculi.

Renovascular hypertension with unilateral atherosclerotic renal artery occlusion: diagnostic use of renal vein renins

Selective renal vein renin studies were performed in seven male patients with severe hypertension and atherosclerotic occlusion of a main renal artery. In five patients, peripheral plasma renin activity was increased, and there was evidence for hypersecretion of renin from the affected kidney and suppression of renin release from the opposite kidney. In one patient, who had occlusion of one renal artery and a high-degree stenosis of the contralateral renal artery, the two kidneys appeared to contribute equally to the high circulating plasma renin activity. Removal of the atrophic, ischemic kidney from these patients, plus bypass of the contralateral renal artery in one patient, resulted in cure or improvement of their hypertension. In one patient, despite hypersecretion of renin from the atrophic kidney, surgery was not recommended because his systemic blood plasma renin activity was not elevated. Histologic examination of the excised kidneys revealed moderate glomerular scarring and tubular atrophy. The findings indicate that the same criteria, derived from renal vein renin studies, that have been used to predict the outcome of surgical repair of renal artery stenosis in hypertensive patients can be applied to the evaluation of patients with hypertension and complete occlusion of a main renal artery.

Angiographic assessment of peritoneovenous shunt malfunction

On 12 patients with reaccumulation of ascitic fluid after peritoneovenous (LeVeen) shunt insertion, shuntograms were performed by direct percutaneous puncture of the venous limb of the shunt. Shunt function was evaluated by pressure determination and injection of sterile iodinated contrast material. The shuntogram correctly predicted the cause of shunt malfunction in ten of 12 patients. Two failures were attributable to central venous hypertension. The addition of pressure measurements has been shown to correlate with central venous pressure at the time of surgery and hopefully will eliminate the inability of the procedure to diagnose shunt malfunction secondary to venous hypertension. There have been no episodes of pulmonary embolization is a safe and effective method for assessing peritoneovenous shunt malfunction. The information gained from this procedure is valuable to the surgeon who plans an operation to correct shunt malfunction.

Transient superior vena cava syndrome due to propylthiouracil therapy in intrathoracic goiter

Intrathoracic goiter is a rare cause of superior vena cava syndrome. We present the findings in a patient in whom the syndrome was precipitated by therapy with propylthiouracil and remitted on withdrawal of the medication. The superior vena cava syndrome did not recur on medical management, suggesting that surgery is not always indicated in this setting.

Pharmacokinetics of nicotine in rats after single-cigarette smoke inhalation

The amount of nicotine absorbed following cigarette smoke inhalation was evaluated by comparing the area under the plasma concentration--time curve and urinary recovery with those observed after its intravenous injection to rats. Nicotine was adsorbed rapidly, with the maximum plasma concentration occurring immediately after cessation of cigarette smoke exposure. On the average, 68% of the nicotine delivered to the inhalation chamber was absorbed. The absorption and elimination of nicotine, as well as the formation and elimination of its metabolites, followed first-order kinetics, and the derived pharmacokinetic parameters were similar to those observed after the intravenous administration of nicotine.

Divergent effects of long acting cyclic nucleotides and lysine vasopressin on the release of matrix sulfated proteoglycans into the medium of fetal rat chondrocytes in monolayer culture

Release of sulfated proteoglycans into the medium of fetal rat chondrocytes in monolayer culture was studied by contrasting the effects of 10% calf serum, long-acting cyclic nucleotides (8 Br-cAMP or DBcAMP), and lysine vasopressin (LVP). Eight hours after initiation of the experiment, the monolayer was pulsed for 2 hours with Na2[35SO4=], the radioactivity was chased, and the monolayer was reincubated for 6 hours with conditioned medium from replicate cultures. Immediately after labelling, the amount of newly synthesized sulfated proteglycans was invariably higher in the insoluble matrix than in the medium compartment. Both additives selectively enhanced sulfate incorporation into chondroitin sulfate of the matrix when compared to serum controls, but only LVP stimulation caused increases in the medium. Remodeling (loss of cell layer and release into the medium at 6 hours) was suppressed by cAMP analogues and increased by LVP. This process was more active in cultures of lower cell density. Utilizing calibrated gel columns, no size difference of the glycosaminoglycans was found between the medium and cell layer compartments of the three treatment groups at the two time points. Because the cAMP analogues inhibit, while LVP stimulates cell division, our observations imply that the rate of degradation of the constraining matrix is increased when replication is favored, even when chondriotin sulfate synthesis is selectively stimulated.