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Variation in hepatitis B immunization coverage rates associated with provider practices after the temporary suspension of the birth dose.

BACKGROUND: In 1999, the American Academy of Pediatrics and U.S. Public Health Service recommended suspending the birth dose of hepatitis B vaccine due to concerns about potential mercury exposure. A previous report found that overall national hepatitis B vaccination coverage rates decreased in association with the suspension. It is unknown whether this underimmunization occurred uniformly or was associated with how providers changed their practices for the timing of hepatitis B vaccine doses. We evaluate the impact of the birth dose suspension on underimmunization for the hepatitis B vaccine series among 24-month-olds in five large provider groups and describe provider practices potentially associated with underimmunization following the suspension. METHODS: Retrospective cohort study of children enrolled in five large provider groups in the United States (A-E). Logistic regression was used to evaluate the association between the birth dose suspension and a child's probability of being underimmunized at 24 months for the hepatitis B vaccine series. RESULTS: Prior to July 1999, the percent of children who received a hepatitis B vaccination at birth varied widely (3% to 90%) across the five provider groups. After the national recommendation to suspend the hepatitis B birth dose, the percent of children who received a hepatitis B vaccination at birth decreased in all provider groups, and this trend persisted after the policy was reversed. The most substantial decreases were observed in the two provider groups that shifted the first hepatitis B dose from birth to 5-6 months of age. Accounting for temporal trend, children in these two provider groups were significantly more likely to be underimmunized for the hepatitis B series at 24 months of age if they were in the birth dose suspension cohort compared with baseline (Group D OR 2.7, 95% CI 1.7-4.4; Group E OR 3.1, 95% CI 2.3-4.2). This represented 6% more children in Group D and 9% more children in Group E who were underimmunized in the suspension cohort compared with baseline. Children in the reversal cohort in these groups remained significantly more likely to be underimmunized compared with baseline. In contrast, in a third provider group where the typical timing of the third dose was unchanged and in two other provider groups whose hepatitis B vaccination schedules were unaffected by the birth dose suspension, hepatitis B vaccination coverage either was maintained or improved. CONCLUSION: When the hepatitis B birth dose was suspended, provider groups that moved the first dose of vaccination to 5-6 months of age or later had decreases in hepatitis B vaccine coverage at 24 months. These findings suggest that as vaccine policy changes occur, providers could attempt to minimize underimmunization by adopting vaccination schedules that minimize delays in the recommended timing of vaccine doses.

Cohort Studies↗

Determination of the changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue.

The purpose of this study was to determine changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue. This study also attempted to determine the possible relationship between the predictive factors of intubation difficulty by using the intubation difficulty scale, which was introduced by Adnet et al., duration of suspension laryngoscopy and changes in hypoglossal nerve function after suspension laryngoscopy. The study was performed on 39 patients who underwent suspension laryngoscopy for benign glottic pathology. Pre-operative airway assessment was evaluated by the intubation difficulty scale and the duration of suspension laryngoscopy was recorded. Needle electromyography of the tongue was performed three or four weeks after the suspension laryngoscopy. After needle electromyography of the tongue, increased polyphasia was found in 13 patients (33 per cent), bilaterally in three of them. The interference pattern was reduced in two of these 13 patients. There was no statistically significant difference in predictive factors of intubation difficulty and the duration of the operation between these 13 patients with increased polyphasia and the remaining 26 patients with completely normal electromyography findings. These findings show that, in spite of normal clinical tongue function, subclinical changes can be detected by needle electromyography of the tongue after suspension laryngoscopy.

Adolescent↗

Tail suspension induces bone loss in skeletally mature mice in the C57BL/6J strain but not in the C3H/HeJ strain.

We assessed the effects of tail-suspension in two skeletal genetic backgrounds, the high C3H/HeJ (C3H) and low C57BL/6J (B6) bone masses inbred mice (male, 4-months old). Cancellous bone mass and structural parameters were evaluated in distal femoral metaphysis by three dimensional microcomputed tomography. Bone cellular activities were evaluated by histomorphometry and measurements of alkaline phosphatase activity (ALP) and osteocalcin in blood and deoxypyridinoline (D-pyr) in urine. In C3H mice, 2- and 3-week unloading experiments were performed. After an early and transient decrease in body weight, a 2-week suspension period resulted in stimulation of both bone formation rate by 45% and active osteoclastic surfaces by 19%. D-pyr did not change, but ALP and osteocalcin levels increased by 18% and 72%, respectively, in 2-week suspended mice, and osteocalcin remained elevated by 30% in the 3-week suspended mice. Such cellular modifications allowed the C3H mice to maintain their initial bone mass and trabecular structural parameters even after a 3-week suspension period. In B6 mice, 1- and 2-week unloading experiments were performed. Tail suspension resulted in decreased body weight during the first days followed by an incomplete recovery during the second week of unloading. The resorption activity was unaffected by any suspension time period, whereas a decrease of 42.5% in bone formation rate and of 21.5% in ALP were seen by the end of the first week of suspension, both values being restored after a 2-week suspension period. At this latter time, trabeculae were thinner, leading to a 24.5% cancellous bone loss. Trabecular number and connectivity, rod-plate index, and degree of anisotropy were not modified. We concluded that C3H mice constituted a unique model in which genetic background overwhelmed the usual effects of reduced biomechanical usage in bone, whereas B6 mice, compared with the standardized rat model, offered an alternative model of bone loss in a mature skeleton.

Animals↗

Flocculation of Bacillus thuringiensis var. israelensis suspension and its efficacy against mosquito larvae.

Bacillus thuringiensis ssp. israelensis (Bti) is increasingly used as an ecologically friendly anti-mosquito agent. The bacterium cells undergo fermentation in dilute suspensions; before practical use, therefore it is necessary to concentrate the suspensions. Aggregation by polymers is a powerful tool with which to regulate the stability of suspensions. Typically, polymers at low concentrations destabilize and at high concentrations stabilize colloidal systems. Bti suspensions can be flocculated efficiently by either cationic or anionic polyelectrolytes. Cationic polyelectolytes were found to be the most efficient flocculants for bacterial suspensions. It was shown that the degree of toxicity of the flocculated Bti suspensions for biting mosquito larvae was in the same range than in non-flocculated suspension.

Animals↗

Cardiorespiratory response to free suspension simulating the situation between fall and rescue in a rock climbing accident.

Many factors contribute to the risk of late death after successful rescue in a rock climbing accident. One factor may be hemodynamic and respiratory compromise by free suspension in a rope between fall and rescue. The risk probably results from using a chest harness alone or the combination of a chest harness and a sit harness. No trials on the acute cardiorespiratory response to free suspension in rock climbing have been reported so far. The effect of 3 min free suspension in a chest harness or in a sit harness on cardiopulmonary parameters was investigated in a randomized, cross-over trial in six healthy volunteers in a simulated rock climbing accident. Measurements were performed before and during the suspension at an altitude of 171 m. No statistical change in cardiopulmonary parameters was observed after free suspension in the sit harness. After free suspension in the chest harness, mean forced vital capacity decreased by 34.3% and mean forced expiratory volume decreased by 30.6%. No statistical change of arterial oxygen saturation occurred and mean end-tidal carbon dioxide increased by 11.5%. Mean heart rate decreased by 11.7%, mean systolic blood pressure decreased by 27.6%, mean diastolic blood pressure decreased by 13.1%, and mean cardiac output decreased by 36.4%. The p value for all reported changes was <0.05. We conclude that free suspension in a chest harness leads to a dramatic impairment of hemodynamics and respiration. This may contribute to the risk of a fatal outcome if rescue is not timely.

Accidental Falls↗

Comparison of interface pressures with pin and suction suspension systems.

A common mode of limb suspension for transtibial amputees is the pin liner/shuttle lock system. Despite its popularity, some clinicians question its use because of observed daily and chronic changes to the residual limb. For this study, we measured limb interface pressures during ambulation with pin and suction suspension systems. No pressure differences were seen between the modes of suspension during stance phase. However, during swing phase, pin suspension maintained an average occlusive compressive pressure of 6.7 kPa on the proximal tissues, as compared to the subocclusive pressure of 1.1 kPa with suction suspension. Simultaneously, pin suspension elevated the peak magnitude of suction to -39.5 kPa at the distal residual limb, compared to -26.1 kPa with suction suspension. During swing phase, the pin liner squeezes proximally while creating a large suction distally on the residual limb and is the likely cause of daily and chronic skin changes observed in pin users.

Adult↗

Viscosity measurements of suspensions of hemoglobin-containing liposomes of varying lipid composition.

The viscosity of suspensions of hemoglobin-containing liposomes (Hb liposomes) and of liposomes without Hb was determined as a function of the shear rate. Liposomes of varying lipid composition were prepared by detergent dialysis. All liposome suspensions showed non-Newtonian viscous behavior, as did erythrocyte suspensions. The viscosity of suspensions of Hb liposomes with a bilayer consisting of egg yolk lecithin and phosphatidylserine was almost identical to erythrocyte suspension viscosity. When cholesterol was included in the lipid component of the Hb liposomes, the dependence of viscosity on the shear rate decreased (flattening of the curve), but overall suspension viscosity became higher than that of erythrocyte suspensions. Evidence is provided for the lipid concentration at which liposomes can be applied intravenously.

Blood Substitutes↗

Vascularization and microvascular permeability in solid versus cell-suspension embryonic neural grafts.

Vascularization and microvascular permeability were assessed in a comparative study of solid (organized) and cell-suspension (dissociated) fetal nigral grafts implanted in the dopamine-deprived striatum of adult rats. Both graft types were analyzed by chromogen detection of intravenously injected horseradish peroxidase (HRP), which outlined vessel walls, and, in cases in which the blood-brain barrier was compromised, permeated the graft and host parenchyma. Survival of graft-derived dopaminergic cells was assessed using tyrosine hydroxylase (TH) immunocytochemistry. Glial reactivity to cell-suspension grafts was similarly assessed with an antibody directed against glial fibrillary acidic protein. Morphometry revealed significantly higher microvessel density in the cell-suspension grafts (p < 0.001), which effectively equaled that found in the contralateral striatum despite rather prominent surrounding glial reactivity. Capillaries in the cell-suspension grafts were not permeable to blood-borne HRP at postimplantation study times of 7, 14, and 30 days whereas, in the solid grafts, permeability in some cases could be detected for up to 30 days. Large numbers of cells immunoreactive for TH were seen in cell-suspension grafts; in contrast, few if any were found in the majority of solid transplants. The multiple-fragment solid graft implant model used clinically compares poorly with the cell-suspension model because it lacks consistency in early revascularization and shows a greater (albeit temporary) tendency for blood-brain barrier dysfunction. Delayed and inadequate vascularization of the solid graft is likely to account for graft failure more often than in the cell-suspension graft. Similarly, a certain critical number of specific grafted cells are required to achieve sufficient expression to bring about a favorable response in the disabled host, and this expression appears to be achieved less consistently with the solid implant technique.

Animals↗

An evaluation of cultivated corneal limbal epithelial cells, using cell-suspension culture.

PURPOSE: A previous report has described an ocular surface reconstruction method involving the use of cultivated corneal epithelium derived from limbal explants. In the current study, a new culture system was developed involving the in vitro propagation on amniotic membrane (AM) of epithelial cells from enzymatically dissociated limbal epithelium. The purpose of this new method is to produce a cultivated epithelial cell layer that contains stem cells and that is superior to explanted cultivated epithelium. The new cell-suspension technique was compared with the existing explant method. METHODS: Limbal epithelial cells were dissociated from donor eyes by dispase and seeded on the denuded AM. Small pieces of limbal epithelium were also cultured on denuded AM as explant cultures. The cultivated epithelium was examined by electron microscopy and immunohistochemistry for cornea-specific keratins (K3 and K12). RESULTS: Both cell-suspension and explant culture methods produced a healthy epithelial cell layer. The cell-suspension culture had significantly (P < 0.001) more desmosomal junctions between the explant-cultured basal cells. In addition, the intercellular spaces between the cell-suspension's basal cells were significantly (P < 0.001) smaller than those between the explant-cultured basal cells. Both types of cultivated epithelium showed positive expression of K3 and K12 keratins. In the cell-suspension culture, expression of K3 and K12 keratins was more prominent in the superficial cells. CONCLUSIONS: Corneal epithelial cells were successfully regenerated in vitro by a cell-suspension culture system. The suspension-cultured epithelium must include some stem cells and morphologically is significantly superior to explant-cultured epithelium. Thus, this new technique is potentially more suitable for cultivated corneal limbal epithelial transplantation.

3T3 Cells↗

Detergent-resistant cytoskeleton of the surface-activated platelet differs from the suspension-activated platelet cytoskeleton.

This study contrasts the protein composition of the detergent-resistant cytoskeleton of platelets fully spread on glass with the cytoskeletal composition of resting platelets and platelets aggregated in suspension with thrombin. Complete Triton X-100-insoluble cytoskeletons were isolated from spread, resting, and suspension-activated platelets in the presence of protease inhibitors, solubilized in sodium dodecyl sulfate/EDTA and analyzed on reduced, one-dimensional polyacrylamide gels. The protein composition of the cytoskeletons differed both qualitatively and quantitatively. Most notable were more extensive incorporation of total protein, talin, and vinculin into the cytoskeleton of spread platelets than the cytoskeleton of suspension-activated platelets. Varying the concentration and time of exposure to thrombin during suspension activation did not mimic the cytoskeletal changes of surface activation. Scanning electron microscopy, measurement of lipid phosphorus content, and varying the duration of Triton extraction did not show incomplete solubilization or nonspecific trapping of constituents in the spread platelet cytoskeleton. Proteolysis of talin was minimal in suspension-activated platelets and in platelets spread for 50 minutes. The differences in the detergent-resistant cytoskeletons of surface- and suspension-activated platelets indicate significant divergence in the physiologies of platelet spreading on surfaces and platelet activation in suspension.

Adult↗

[Enhancement of hypericin production and cell growth of Hypericum perforatum L. suspension cultures by nitric oxide].

Nitric oxide has emerged as a key signaling molecule in plants recently. The role of nitric oxide in elicitor-induced defense responses of plants has been extensively investigated. In this work, sodium nitroprusside was utilized as the donor of nitric oxide to investigate the effects of exogenous nitric oxide on hypericin production and cell growth of suspension cell cultures of Hypericum perforatum L.. Compared with the untreated Hypericum perforatum L. suspension cells, external application of 0.5 and 15.0 mmol/L sodium nitroprusside induced 1.4 and 0.5-fold dry cell weight, and 0.9 and 2.1-fold hypericin content respectively. The results showed that low concentration of sodium nitroprusside promoted the growth of Hypericum perforatum L. suspension cells, while high concentration of sodium nitroprusside enhanced hypericin biosynthesis in Hypericum perforatum L. suspension cells. The maximum hypericin production was achieved by adding 0.5 mmol/L and 15.0 mmol/L sodium nitroprusside to the culture at day 0 and day 14 respectively, increasing the total hypericin yield by nearly 3.2-fold. The effects of sodium nitroprusside on hypericin content and growth of Hypericum perforatum L. suspension cells were abolished by nitric oxide specific scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, which indicated that the effects of the application of sodium nitroprusside were caused by nitric oxide released from sodium nitroprusside rather than sodium nitroprusside itself. The results also showed that 15.0 mmol/L sodium nitroprusside stimulated the activities of phenylalanine ammonia-lyase (PAL), one of the key enzymes of phenylpropanoid pathway, in suspension cells of Hypericum perforatum L., which suggested that the synthetic pathway of hypericin might be activated by NO through triggering the defense responses of Hypericum perforatum L. suspension cells.

Anthracenes↗

A comparison of endoscopic suspension of the vesical neck versus anterior urethropexy for the treatment of stress urinary incontinence.

Endoscopic suspension of the vesical neck has been reported to be as effective as anterior urethropexy in the treatment of female stress urinary incontinence. We compared our first 29 patients treated with endoscopic suspension of the vesical neck between 1982 and 1985 to our last 21 patients treated with anterior urethropexy between 1979 and 1985. Both groups were comparable in regard to age, parity, duration of symptoms and previous surgery for stress urinary incontinence. All patients underwent thorough preoperative urodynamic testing. Endoscopic suspension of the vesical neck successfully cured stress urinary incontinence in 26 patients (90 per cent), while anterior urethropexy resolved the incontinence in 20 (95 per cent). Of the 3 failures of endoscopic suspension 2 probably were related to technique or material failure. Hospitalization was reduced for endoscopic suspension versus anterior urethropexy (mean 4.04 versus 6.00 days, respectively). The most common complication after endoscopic suspension of the vesical neck was transient urinary retention (34 per cent). We conclude that endoscopic suspension of the vesical neck is an effective method to treat stress urinary incontinence, and that it also reduces hospital stay and postoperative recovery.

Endoscopy↗

Early central venous pressure changes in the rat during two different levels of head-down suspension.

The head-down suspension (i.e. antiorthostatic hypokinesia) rat is used to simulate the circulatory effects of weightlessness. However, little is known about the early cardiovascular adaptive response to simulated weightlessness and the effects of varying degrees of head-down suspension. Therefore, the purpose of this study was to characterize the early central venous pressure changes to two different levels of head-down suspension in the rat. Unanesthetized, unrestrained, female Sprague-Dawley rats (wt: 298 +/- 18 gms, mean +/- S.D.) with chronically implanted central venous pressure catheters were subjected to either a 45 degrees C head-down tilt angle (Group A, N = 8) or a 20 degrees head-down tilt angle (Group B, N = 8) using the tail-traction technique of head-down suspension. Central venous pressure increased significantly (p less than 0.05) in both groups of rats during head-down suspension with the absolute pressure level significantly (p less than 0.05) higher in Group A rats compared to Group B rats during the first 8 h of the study. At 24 h, the rats in Group B appeared to adapt earlier to head-down suspension because central venous pressure decreased to the previous baseline level whereas it remained increased in Group A rats. We conclude that the level of head-down suspension significantly affects the early central venous pressure response and subsequent cardiovascular adaption to simulated weightlessness in rats.

Animals↗

Energy costs of below-knee prostheses using two types of suspension.

The choice of suspension in below-knee prosthetics poses a problem for the clinician because cuff suspension weighs less than side-joint-thigh corset suspension but the latter offers more stability. The energy costs of one compared with the other is of prime consideration when dealing with the older person after an amputation. To determine the energy costs of cuff and side-joint-thigh corset suspension, 17 patients were selected for study. A sepcial prosthetic bucket was fabricated for each patient and designed so that the suspensions could be quickly and easily interchanged. Trials with each method of suspension were carried out before and after a training period, and the cardiorespiratory parameters were measured. After the training period all patients demonstrated less oxygen consumption, but the type of suspension did not affect energy costs.

Adolescent↗

Flocculation of sulfamerazine suspensions by a cationic polymer.

Flocculation by a cationic polymer of sulfamerazine suspensions containing a wetting agent was evaluated. Suspensions with sufficient surfactant concentrations to ensure complete wetting were deflocculated. When the anionic surfactant, dioctyl sodium sulfosuccinate, was used as a wetting agent, the suspensions were flocculated over a limited polymer concentration range. Flocculation was attributed to simultaneous interaction of a polymer molecule with more than one particle. At higher polymer concentrations, the particles were covered completely with polymer, leading to repulsion between the particles and deflocculation of the suspensions. The polymer concentration required for flocculation provided evidence for interaction between the anionic surfactant and the cationic polymer. Suspensions containing a nonionic surfactant also were flocculated using various polymer concentrations. When a surfactant mixture was employed in the suspensions, the peak sedimentation volume of flocculated systems and the concentration of polymer at the peak depended on the surfactant mixture composition.

Cations↗

Correlation between the bioavailability of microencapsulated bacampicillin hydrochloride in suspension and in vitro microcapsule dissolution.

The relative bioavailability of microencapsulated bacampicillin hydrochloride in suspension was correlated with the in vitro dissolution half-lives of the microcapsules. Simultaneously, a sensory evaluation was performed to evaluate the taste acceptability of the suspension. The in vitro dissolution half-life is directly related to the coating thickness of the microcapsules. The four suspensions of bacampicillin hydrochloride, containing microcapsules with different coating thickness, were given as single 400-mg oral doses to 12 healthy volunteers after overnight fasting using a crossover design with balanced sequences. Bacampicillin is a prodrug of ampicillin, the concentration of which was determined in plasma and urine by bioassay. There were significant inverse linear relationships between the dissolution half-life and plasma peak concentration, area under the curve, and urinary recovery. The terminal exponential disposition phases of the curves were similar for all four suspensions. There was a significant direct linear relationship between the dissolution half-life and overall taste and bitterness. The results show that the mean bioavailability of bacampicillin hydrochloride from a microcapsule suspension can be predicted from an in vitro dissolution half-life. The results also suggest that bacampicillin hydrochloride can be given in a suspension with sufficient microcapsule film thickness to reduce the bitter taste of the drug and still retain adequate bioavailability.

Adult↗

Interpretation of the hindered settling of calcium carbonate suspensions in terms of permeability.

Many pharmaceutical formulations are produced in the form of concentrated suspensions. Calcium carbonate suspensions are used in this study and interpreted as the "model" for the behavior of such suspensions. The behavior of concentrated suspensions of powders in a liquid medium cannot be treated by the simple application of the normal principles of free fall and the use of Stokes Law pertaining to the viscous resistance offered by the surrounding fluid to fall. A single particle operating by the Stokes principle obeys this relationship. This law applies to the behavior of particles at low concentration in a liquid medium and is the basis for particle size distribution methods. At higher concentrations, however, the particles do not enjoy the freedom of unhindered fall. The system subsides "en bloc," and it is common practice to offer a modification to the Stokes equation which takes into consideration some function of the porosity of the system. There have been a considerable number of equations developed and modified based on this principle. However, an alternative method is to approach the problem by dealing with the permeability of a bed of powders in a liquid in which the bed is slowly altering with time. This is best achieved by the use of the permeability equation developed and presented by Kozeny-Carmen. This equation, as well as the Richardson-Zaki expression, are related to show that the Kozeny parameter K varies with the suspension porosity under sedimentation conditions. The values of K are often larger than the value normally reported (i.e., approximately 5). The data and treatment outlined here are extended to include not only the calcium carbonate suspensions, but other systems previously mentioned in the literature.

Calcium Carbonate↗

Bovine adrenal chromaffin cells: high-yield purification and viability in suspension culture.

A method for purifying chromaffin cells from adult, bovine, adrenal medullae and the techniques for maintaining the cells in suspension culture for at least 14 days are presented. Perfusion of medullae with a collagenase-containing medium produced a cell fraction that contained, in addition to chromaffin cells, a significant percentage of non-chromaffin cells. These cells were found to attach more rapidly than chromaffin cells to glass and tissue-culture plasticware. Using this property, we devised a selective plating procedure that yielded approximately 1-2 x 10(8) chromaffin cells per adrenal medulla at a purity of 95% or higher. On the basis of catecholamine levels and enzyme activities, suspension (as opposed to monolayer) cultures were chosen to further investigate their potential as a model system for the regulation of adrenergic function. In contrast to chromaffin cells cultured in monolayer, chromaffin cells in suspension had a more rounded appearance and formed multicellular aggregates with time in culture. Very few neurite-like structures, commonly observed in monolayer cultures, were present in the suspension cultures. Also, inhibitors of mitosis were not necessary to prevent overgrowth by non-chromaffin cells as there was little or no cell division in the suspension cultures. Catecholamine levels were relatively stable for at least 2 weeks, although a gradual decline in epinephrine occurred after day 5. Unlike other enzymes involved in catecholamine metabolism, phenylethanolamine N-methyl transferase activity declined significantly with time in culture in parallel to the gradual loss of epinephrine. In addition, both oxygen consumption and amino acid incorporation into proteins were relatively stable. Thus, the primary suspension cultures of adult, bovine chromaffin cells seem to offer several advantages for studying long-term regulation of chromaffin cell function and provide a stable source of adrenergic cells for examining short-term regulatory processes.

Adrenal Medulla↗