An analysis of the effect of venous resistance on the performance of gravity-fed intravenous infusion systems

OBJECTIVE: Our objective was to assess the effect of venous resistance in a clinically relevant range on flow rates through intravenous (i.v.) cannulae. METHODS: Since resistances in series are additive, the sum of the resistance of the i.v. cannula and the vein equates to the total resistance to flow. Using resistance data from earlier work, the total resistance for various combinations of cannula and vein size was calculated, allowing a prediction to be made of the comparative flow rates between these combinations for a given driving pressure. Next, the clinical situation was simulated by measuring flow rates through i.v. cannulae connected in series to a variety of infusion devices with resistances known to be within the range of clinically relevant venous resistance. RESULTS: The effect of venous resistance was greatest on large-bore cannulae, with significant reductions in flow occurring when even low levels of venous resistance were added. Throughout much of the range of venous resistances encountered clinically, total flows through two small-gauge cannulae exceeded that through a single large-gauge cannula. CONCLUSION: To achieve maximum benefit from a large-bore cannula, a suitably large vein must be chosen. Further, where venous access is difficult and high flow potential from an infusion system is required, two separate infusions through small cannulae may be a preferable option to a single large bore.     

The use of nonhomologous scatchard analysis in the evaluation of ligand-protein interactions

Scatchard plots are widely used for the graphical presentation of receptor-ligand binding data. When a combination of labelled and unlabelled ligand molecules is used in a binding assay, equations for Scatchard plots are readily available if the labelled and unlabelled ligands have similar binding affinities. In this article, Everardus van Zoelen, Roel Kramer, Herman van Moerkerk and Jacques Veerkamp present mathematical equations to obtain the binding characteristics of an unlabelled ligand in a Scatchard plot, which has a dissociation equilibrium constant different from that of the labelled ligand used.     

Hyperhomocysteinemia and atherosclerotic vascular disease: pathophysiology, screening, and treatment. off

Hyperhomocysteinemia has recently been identified as an important risk factor for atherosclerotic vascular disease. This article reviews homocysteine metabolism, causes of hyperhomocysteinemia, the pathophysiological findings of this disorder, and epidemiological studies of homocysteine and vascular disease. Screening for hyperhomocysteinemia should be considered for patients at high risk for vascular disease or abnormalities of homocysteine metabolism. For primary prevention of vascular disease, treatment of patients with homocysteine levels of 14 micromol/L or higher should be considered. For secondary prevention, treatment of patients with homocysteine levels of 11 micromol/L or higher should be considered. Treatment is most conveniently administered as a folic acid supplement (400-1000 microg) and a high-potency multivitamin that contains at least 400 microg of folate. Higher doses of folic acid and cyanocobalamin supplements may be required in some patients. Until prospective clinical trial data become available, these conservative recommendations provide a safe, effective, and evidence-based approach to the diagnosis, evaluation, and management of patients with hyperhomocysteinemia.     

Psychological stress, occurrence of cancer and cause-specific mortality]

Psychological stress has been claimed to contribute to the onset of cancer and to increase mortality from a number of nonmalignant diseases. We investigated the effect of a genuine psychological stressor, i.e. cancer in a child, on the incidence of cancer and mortality from nonmalignant diseases of 11,231 parents in a Danish nationwide population-based study. The children were identified from records in the Danish Cancer Registry for the period 1943-1985; their parents were identified from population registers. Overall, 1665 parental malignancies were diagnosed from the date the cancer of the child was reported through 1992, as compared with 1702 expected from national incidence rates, to yield standardized incidence ratios of 1.0 (95% confidence interval, 0.9-1.0) for all parents, 1.0 for mothers and 1.0 for fathers. No excess mortality was seen from causes associated with allergic illness, autoimmune conditions, chronic illness or changes in behaviour. Our data provide no support for the hypothesis of an association between psychological stress and the incidence of cancer or mortality from nonmalignant diseases. We conclude that the human organism is highly adaptable, even to extreme psychological stress.     

Isolation and characterization of tilapia (Oreochromis mossambicus) insulin-like growth factors gene and proximal promoter region

It has been shown that both multidrug resistance-associated protein (MRP1) and canalicular multispecific organic anion transporter (cMOAT/MRP2) have the ability to extrude glutathione conjugates (GS-X pump activity)from cells. Therefore, they play an important role in the detoxification of xenobiotics. Using mrp1-knockout mice, it has recently been shown that MRP1/mrp1 has an important role in the export of leukotriene C4 (LTC4), a mediator of inflammation, and in protecting the body from a number of toxins, including several antitumor drugs. A comparison of the transport properties across the bile canalicular membrane in normal and mutant rats, whose cMOAT function is hereditarily defective, has shown that the physiologic role of cMOAT is to excrete LTC4, bilirubin glucuronides, 171-estradiol-170-D-glucuronide, and reduced folates. In the present review article, we summarize the substrate specificity and mechanism for the transport of these GS-X pumps, focusing on the pharmacologic and physiologic aspects. The transport activity mediated by cMOAT is also discussed in terms of a comparison between membrane vesicles from hepatocytes and cMOAT-transfected cells, and we also briefly examine the possible role of MRPI and cMOAT in the extrusion of reduced glutathione.     

Occupational medicine in general practice. A study of the extent and nature of occupational injuries in the county of Ringkj?bing

The purpose of this investigation was to estimate the occurrence and type of work-related incidents in primary health care in the county of Ringkoebing, Denmark, with 270,000 inhabitants. Symptom-related general practitioner (GP)-consultations among 17-66 year-old residents were registered among 114 GP's during four days over one year. In each occasion the GP evaluated the question of work-relatedness versus none-work-relatedness. Of 3017 registered consultations, 479 were work-related (15.9%). There were 376 disease cases and 103 injury cases. Musculoskeletal diseases constituted the dominating diagnostic category, as well as being the category with the highest proportion of work-relatedness, corresponding to 35% of all musculoskeletal consultations. Notification as a work injury case was performed for 19% of all work-related cases. This investigation represents the hitherto most extensive Danish material of the distribution of work-related incidents within the broad spectrum of the GP's practice.     

Increasing the dose and rate of Albunex infusion leads to superior left ventricular contrast effect

In routine clinical use, the efficacy of Albunex in producing clinically useful opacification may be lower than in initial clinical studies. We hypothesized that increasing either the rate of injection or amount of Albunex administered would increase left ventricular opacification. Fifty adult volunteers were each injected with Albunex in five volume/rate combinations. Blinded reviewers evaluated left ventricular opacification and endocardial border delineation compared with the baseline (noncontrast) echocardiogram. In addition, captured digitized images were analyzed with video-densitometric techniques. Injected at the highest volume/rate tested (20 ml at 3.0 ml/sec), Albunex provided the greatest improvement in left ventricular opacification, endocardial border delineation, and quality of the echocardiogram. The administration of Albunex caused no serious adverse events at any volume/rate regimen tested. Our data indicate that faster injection rates and larger dose volumes than those currently recommended by the package insert significantly improve Albunex ultrasound contrast without compromising safety.     

Risk of subsequent malignant neoplasms among 1,641 Hodgkin's disease patients diagnosed in childhood and adolescence: a population-based cohort study in the five Nordic countries. Association of the Nordic Cancer Registries and the Nordic Society of Pediatric Hematology and Oncology

PURPOSE: To assess the risk of subsequent malignant neoplasms among Hodgkin's disease patients diagnosed before 20 years of age in the five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden). PATIENTS AND METHODS: There were 1,641 Hodgkin's disease patients identified through the national cancer registries since the 1940s or 1950s. The patients were monitored for 17,000 person-years until the end of 1991. Expected figures were derived from the age-specific incidence rates in each country and standardized incidence ratios (SIR) were calculated. RESULTS: A total of 62 subsequent neoplasms were diagnosed (SIR, 7.7; 95% confidence interval [CI], 5.9 to 9.9). The overall cumulative risk of subsequent neoplasms was 1.9% at the 10-year follow-up point, 6.9% at 20 years, and 18% at 30 years. There were 26 subsequent neoplasms among males (SIR, 6.5; 95% CI, 4.3 to 9.6) and 36 among females (SIR, 8.9; 95% CI, 6.2 to 12), of which 16 were breast cancers (SIR, 17; 95% CI, 9.9 to 28). High risks were seen for thyroid cancer (SIR, 33; 95% CI, 15 to 62), for secondary leukemia (SIR, 17; 95% CI, 6.9 to 35), and for non-Hodgkin's lymphoma (SIR, 15; 95% CI, 4.9 to 35). The relative risk increased from 3.3 (95% CI, 1.2 to 7.1) for Hodgkin's disease patients diagnosed in the 1940s and 1950s to 15 (95% CI, 7.4 to 27) in the 1980s. The highest risk of secondary leukemia (SIR, 68; 95% CI, 18 to 174) was seen among those diagnosed with Hodgkin's disease in the 1980s. CONCLUSION: Patients who survive Hodgkin's disease at a young age are at very high relative risk of subsequent malignant neoplasms throughout their lives. In particular, the high relative risk of breast cancer following Hodgkin's disease in the teenage years calls for enhanced activity for early diagnosis.     

A three-dimensional computerized mesh diagram analysis and its application in soft tissue facial morphometry

A modified computerized mesh diagram analysis that allows rapid and independent quantifications of soft tissue facial size and shape in the three-dimensional space is presented. Normal references are provided, and the application of the method is also exemplified by the analysis of two maxillofacial surgical patients. The Three-Dimensional Facial Morphometry method has been used for the collection of the x, y, z coordinates of 22 soft tissue landmarks in 50 men and 50 women (all healthy young white adults). The method detects the three-dimensional coordinates of retroreflective, wireless markers positioned on selected facial landmarks with two charge-coupled device cameras, working in the infrared field. The midpoint between the right and left tragus landmarks served as the origin of the coordinate axes, and the landmark coordinates were rotated, setting the intercantheal line horizontal on both the frontal and the horizontal planes, and the Camper's plane inclined at -7.5 degrees on the sagittal plane. A standardized mesh of equidistant horizontal (dimension: half the upper face width), vertical (half the vertical projection of upper face height), and anteroposterior (half the horizontal projection of upper face depth) lines was consequently constructed. The lattice was replicated on the entire face and comprised 84 parallelepipeds. Both male and female reference meshes had a harmonious and symmetric appearance, with gender differences in facial size but not in facial shape. The standard normal reference was superimposed on the patient's tracing, and the global (size plus shape) difference was then evaluated by the calculation of the relevant displacement vectors for each soft tissue landmark. A global difference factor was calculated as the sum of the modules of all the displacement vectors. Consequently, a size normalization was performed, and the shape difference (size-standardized) was then evaluated by the calculation of new relevant displacement vectors for each landmark, as well as a shape--global difference vectors.     

A statistical analysis of the effect of a mixture component on the rheology of alumina feedstocks

A statistical analysis based on the McLean-Anderson design method was carried out in studying the influence of each formulation component on the flow properties of alumina feedstocks. The formulations were composed of alumina powder (AL), polypropylene resin (PP), paraffin wax (PW), and stearic acid (SA). Fourteen different formulations were designed and their viscosities were measured using a capillary viscometer. The corresponding rheological parameters,i.e., fluidity, pseudoplasticity, and flow energy (ΔE) were evaluated and the effects of each ingredient in the mixture on them were analyzed. The studied ranges of AL, PP, PW, and SA were 87 to 89, 5 to 9.25, 3 to 7.25, and 0.75 to 1.5 wt pct, respectively. The results indicated that the lower alumina content or higher binder content would improve the fluidity of feedstocks. The order of increase in fluidity is SA > PW > PP. An increase of either AL or SA or a decrease of either PP or PW would cause less shear thinning in the resulting mixtures. Polypropylene resin is more effective than PW in enhancing pseudoplasticity. Finally, ΔE of feedstocks first decreases, reaches a minimum value at AL of about 87.7 wt pct, and then increases with powder loading. Increasing SA or decreasing either PP or PW would make ΔE smaller.