Phase I trial of 5-fluorouracil by 24-hour infusion weekly

A novel schedule of 5-fluorouracil administration has been developed for biochemical modulation studies. In combination with the pyrimidine synthesis inhibitor PALA, 5-fluorouracil has been given as a 24-hour infusion, repeated weekly: a dose of 2600 mg/m2 is well tolerated. To identify a suitable dose of 5-fluorouracil as a single agent on this schedule, we treated 26 patients at doses ranging from 2800 to 3400 mg/m2 per week. Two-thirds of the patients had failed previous therapy, and most were symptomatic from their disease. Over half of the patients had metastatic colorectal cancer. The dose-limiting toxicity was diarrhea: Grade 3 or 4 toxicity occurred at every level tested. Twenty-two of the 26 patients required therapy interruption because of toxicity. The severity of this toxicity indicated that escalation of 5-fluorouracil on this schedule beyond the 2600 mg/m2 known to be tolerated in the PALA-containing regimen, would be impractical. Two patients, both with previously untreated colorectal cancer, had partial remissions lasting three and five months respectively. This dose-intense schedule of 5-fluorouracil administration will be explored further in large-scale randomized trials.

Urinary dopamine response to angiotensin II is not abnormal in type 1 (insulin-dependent) diabetes mellitus

To examine the interaction between angiotensin II (ANGII) and dopamine in type 1 diabetes mellitus, urinary dopamine excretion was examined during ANGII infusion in 15 diabetic patients and 10 control subjects after pretreatment with lithium 750 mg and placebo. The antinatriuretic response and the urinary dopamine response to ANGII did not differ within or between the two groups on each study day. No correlation was observed between the decrements in urinary sodium excretion and urinary dopamine output during ANGII infusion in either group. The effect of insulin on urinary dopamine excretion was studied separately in seven non-diabetic subjects; sodium and potassium retention occurred during a hyperinsulinaemic euglycaemic clamp, but urinary dopamine did not change. The data suggest that the relationship between urinary sodium excretion and tubular dopamine synthesis remains normal in early type 1 diabetes mellitus both at baseline and during the antinatriuresis induced by angiotensin II. The cause of the reduction in urinary dopamine during ANGII infusion is unclear, but is probably not mediated directly by changes in proximal tubular sodium transport.

A Process-Oriented Approach: SELECTING A NURSING MODEL FOR PSYCHIATRIC NURSING

The nursing literature is replete with articles and books that describe nursing conceptual frameworks and models and encourage their use in clinical, education, and research activities. Although much information exists on the content of nursing models, less has been written about how a model is to be chosen and the process that may facilitate the choice of a model. This article reviews potential benefits and limitations of nursing models and conceptual frameworks and describes a three-phase process for selecting a model for psychiatric nursing practice.

Learning styles of Chinese nursing faculty and career choice preferences

Chinese nurse educators' learning styles were examined using Kolb's experiential learning theory. Although many Chinese nurses are not able to select a profession for its fit to their personal learning orientation, they exhibit a learning style very similar to Canadian nurses.

Purification and characterization of the reconstitutively active tricarboxylate transporter from rat liver mitochondria

The tricarboxylate transporter has been purified in reconstitutively active form from rat liver mitochondria. The transporter was extracted from mitoplasts with Triton X-114 in the presence of cardiolipin and citrate and was then purified by sequential chromatography on hydroxylapatite, Matrex Gel Orange A, Matrex Gel Blue B, and Affi-Gel 501. Analysis of the purified material via sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated the presence of one main protein band with an apparent molecular mass of 32.5 kDa. Upon incorporation into phospholipid vesicles, the purified transporter catalyzed a 1,2,3-benzenetricarboxylate-sensitive citrate/citrate exchange with a specific transport activity of 3240 nmol/4 min/mg of protein. This value was enhanced 831-fold with respect to the starting material. Substrate competition studies indicated that the reconstituted transport could be substantially inhibited by isocitrate, malate, and phosphoenolpyruvate, but not by alpha-ketoglutarate, succinate, malonate, pyruvate, or inorganic phosphate. Moreover, in addition to 1,2,3-benzenetricarboxylate, the reconstituted exchange was sensitive to the anion transport inhibitor n-butylmalonate but was insensitive to phenylsuccinate, alpha-cyano-4-hydroxycinnamate, and carboxyatractyloside. Finally, studies with covalent modifying agents indicated the purified transporter was inhibited by sulfhydryl reagents and by diethyl pyrocarbonate, 2,3-butanedione, phenylglyoxal, and pyridoxal 5-phosphate. In conclusion, these studies describe the first procedure to yield a highly purified tricarboxylate transport protein that both displays a high specific transport activity and can be obtained in quantities that readily enable further structural as well as functional studies. Based on its substrate specificity and inhibitor sensitivity, the purified 32.5-kDa protein appears to represent the complete tricarboxylate transport system found in rat liver mitochondria. Finally, new information is presented concerning the effect of covalent modifying reagents on the function of this transporter.

Humoral immune responses in mice using gamma inulin preparations as adjuvants for hepatitis B vaccines

There is an urgent need for new, powerful adjuvants suitable for use with sub-unit and peptide vaccines in humans. We have measured the humoral immune response in BALB/c mice to vaccine formulations using recombinant HBsAg antigens, and gamma inulin and alum adjuvants. Using Merck, Sharpe & Dohme (MSD) HBsAg at 10 micrograms/mL, high levels of anti-HBs were generated and geometric mean S/N ratios of 88, 133 and 107 were obtained for alum absorbed vaccine, gamma inulin, and a mixture of the two adjuvants, respectively. A dilution series produced ED50 values of 0.08, 0.15 and 0.22 micrograms/mL respectively. In a second series of experiments comparing alum and algamulin (a complex of gamma inulin and alum), MSD HBsAg induced anti-HBs levels of 81 and 52, and ED50 values of 0.3 and 0.4 when used in conjunction with alum and algamulin, respectively. SKF HBsAg induced anti-HBs levels of 126 and 111 with alum and algamulin, and ED50 values of 0.11 and 0.075. The class, subclass and level of antibody produced in mice boosted with a second dose of vaccine at 21 days was also examined. Both alum and gamma inulin induced higher levels of total antibody, IgG1 and minor IgG subclasses than algamulin, or HBsAg alone. Overall, gamma inulin appears to be an equivalent adjuvant to alum, although their mechanisms of action are different. Mixtures or complexes of the two adjuvants appear to be less effective in inducing humoral immune responses in mice than either alone.

A study of the cells in the explanted viable cryopreserved allograft valve

From June 1975 to December 1987, 231 patients underwent aortic valve replacement with a viable cryopreserved allograft aortic valve. Throughout this era, a uniform procurement and preservation was used to maintain leaflet fibroblast viability. The allograft valve was obtained from coroner's autopsies within 24 hours of death, and more recently from organ donors, incubated for 24 hours in low dose antibiotic solution followed immediately by cryopreservation (mean time interval 39 hours after donor death). Viability was ensured by monitoring glucose utilization of the aortic and pulmonary valves and by demonstrating fibroblast growth in tissue cultured from the pulmonary valve. A uniform protocol for valve preparation was used during the entire experience. Nine allograft aortic valves have been obtained by eight reoperations (two were for leaflet degeneration) and one autopsy. The time intervals from implantation to explantation were 2 months, 10 months, 20 months, 22 months, 2.2 years, 5 years, 8.3 years, 9.2 years, and 10.8 years. Histologic examination of the leaflet tissue disclosed a variable degree of cellularity, ranging from a highly cellular matrix (9.2 years) to minimal cellularity (20 months). Within the same valve (10 months), one leaflet was completely acellular with a moderate degree of cellularity in the other two leaflets. The competent valve recovered at autopsy (8.2 years) was essentially acellular. Fibroblasts could consistently be cultured from leaflets in which viable cells were seen histologically. Chromosomal analysis of cultured cells from a valve leaflet (9.2 years) that was implanted with a donor and recipient sex mismatch demonstrated persistence of donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The hazards of using active clinic patients as a source of subjects for clinical studies

The authors describe and empirically demonstrate a form of bias that results from deriving subjects for clinical studies from available patients currently being followed in specific disease clinics instead of inception cohorts (patients enrolled at a uniform and early point in their disease). They label this effect "clinic patient bias." It is a variation of prevalence-incidence (Neyman) bias in that it also results from the time gap between the onset of a specific characteristic (a risk factor, exposure or disease) and enrollment in the study, causing selective exclusion of fatal or short episodes, or mild or silent cases. Clinic patient bias may distort an estimate of relative risk in either direction. The empirical example is derived from a study of risk factors for developing complications such as peritonitis among end-stage renal disease patients treated with continuous ambulatory peritoneal dialysis (CAPD). The use of available clinic patients rather than an inception cohort (patients newly beginning CAPD) resulted in the demonstration of false apparent risk relationships for two variables: the calendar date when patients began CAPD (with those enrolled at an earlier time appearing to be at lower risk), and serum albumin level at the start of CAPD (with those having lower albumin levels appearing to be at higher risk). This example demonstrates one of the potential hazards of using active or available clinic patients as a source of subjects for clinical studies.

Predicting nutrition-associated complications for patients undergoing gastrointestinal surgery

We studied 202 patients admitted to two major teaching hospitals for planned gastrointestinal surgery to assess the ability of several techniques of nutritional assessment to predict major postoperative complications (infection and/or wound problems). Subjective global assessment (SGA) and albumin were both of predictive value, and combinations of these variables were useful in differentiating low-risk from high-risk patients. Transferrin, creatinine-height index, percent ideal weight, percent body fat, and total lymphocyte count were not useful in predicting complications. We conclude that SGA and albumin are useful "nutritional assessment techniques" for patients undergoing major gastrointestinal surgery if the purpose of such an assessment is to predict postoperative "nutrition-associated complications." The second major finding of this study was the unexpectedly low rate of complications (10%) which was found in both hospitals. We suggest that these low complication rates may be more generalizable to patient populations derived from a wide community base, rather than those described in other studies in which veterans or patients of lower socioeconomic status comprised the sample.

Nutritional assessment of continuous ambulatory peritoneal dialysis patients

This study revealed the following. Malnutrition was frequent (41.6%) in patients on CAPD for less than three months and was present in 18.1% of patients on CAPD for longer than 3 months. Fifty percent of these malnourished patients returned to normal on conventional nutritional management within 2 to 6 months, but 10% remained malnourished throughout the study period. There was increased mortality among malnourished patients, but we were unable to demonstrate that the state of nutrition was an independent risk factor, because of the increased prevalence of other co-morbid risk factors known to influence survival and because of the limitation of a small sample size. The influence, if any, of nutritional state as an independent risk factor on the survival of CAPD patients should be answered, because malnutrition is potentially reversible with aggressive nutritional interventions, such as enteral, parenteral, or intraperitoneal supplementation.

The viable cryopreserved allograft aortic valve

One hundred and twenty-four patients underwent aortic valve replacement with a nonviable 4 degrees C refrigerated aortic allograft valve. One hundred and eighty-four patients underwent aortic valve replacement with a viable cryopreserved aortic allograft valve in a later era. The longest follow-up was 16 years for the group with the nonviable valve and 11 years for the group with the viable valves. Within this time frame, reoperation was required in 23 patients with nonviable valves for leaflet perforation or rupture whereas no patients in the group with viable valves developed this complication (p less than 0.0001). The prevalence of endocarditis and thromboembolism was very low in both groups. Viability of leaflet tissue is associated with an important improvement in durability over nonviable allograft valves. Consequently, long-term follow-up results of allograft valves might be best expressed in terms of viability. The current evidence suggests that the viable cells are donor in origin. The viable cryopreserved aortic allograft valve offers significant advantages over current nonviable allograft valves, mechanical valves, and bioprostheses.

Evaluation of public health preschool child developmental screening: the process and outcomes of a community program

We conducted a randomized controlled trial of a public health and education screening program aimed at all 4,797 four to five year old children registering for kindergarten in three school districts of southern Ontario, Canada. Children received either the Denver Developmental Screening Test (DDST) with a community health intervention program for positive screeness; the DDST with no intervention for positive screenees; or no screening test. The intervention program consisted of referral to the child's physician for assessment; a review conference between the child's teacher and the school health nurse; parent counseling; and monitoring of the child in school by the school health nurse. At the end of the third school year, no differences were found between positive screenees in the community health intervention group and the "no intervention" groups using individual academic achievement, cognitive, and developmental tests. Parents' reports revealed no differences between groups in children's mental, social, and behavioral well-being. However, parents of intervention program children had more worry about their child's school progress suggesting a potentially harmful labeling effect. In comparison to a random sample of children with normal DDST results, or a random sample of children who had randomly not been screened, the children with positive preschool DDSTs had substantially more school problems three years after screening.

What is subjective global assessment of nutritional status?

Presented and described in detail is a clinical technique called subjective global assessment (SGA), which assesses nutritional status based on features of the history and physical examination. Illustrative cases are presented. To clarify further the nature of the SGA, the method was applied before gastrointestinal surgery to 202 hospitalized patients. The primary aim of the study was to determine the extent to which our clinician's SGA ratings were influenced by the individual clinical variables on which the clinicians were taught to base their assessments. Virtually all of these variables were significantly related to SGA class. Multivariate analysis showed that ratings were most affected by loss of subcutaneous tissue, muscle wasting, and weight loss. A high degree of interobserver agreement was found (kappa = 0.78, 95% confidence interval 0.624 to 0.944, p less than 0.001). We conclude that SGA can easily be taught to a variety of clinicians (residents, nurses), and that this technique is reproducible.

Biomedical surveillance: rights conflict with rights

Medical screening and biomedical monitoring violate individual rights. Such conflicts of right with right are acted upon synergistically by uncertainty which, in some important respects, increases rather than decreases as a result of research. Issues of rightness and wrongness, ethical issues, arise because the human beings who are subjects of medical screening and biological monitoring often have little or no option whether to be subjected to them. We identify issues of rightness and wrongness of biomedical surveillance for various purposes of occupational health and safety. We distinguish between social validity and scientific validity. We observe that principles are well established for scientific validity, but not for social validity. We support guidelines as a way forward.

Predicting cardiac complications in patients undergoing non-cardiac surgery

The authors prospectively studied 455 consecutive patients referred to the general medical consultation service for cardiac risk assessment prior to non-cardiac surgery, in order to validate a previously derived multifactorial index in their clinical setting. They also tested a version of the index that they had modified to reflect factors they believed to be important. For patients undergoing major surgery, the original index performed less well in the validation data set than in the original derivation set (p less than 0.05), but still added predictive information to a statistically significant degree (p less than 0.05). The modified index also added predictive information for patients undergoing both major and minor surgery, demonstrating an area under the Receiver Operating Characteristic curve of 0.75 (95% confidence interval of 0.70 to 0.80). A simple nomogram is presented which will enable conversion of pretest probabilities into posttest probabilities using the likelihood ratios associated with each risk score. It is recommended that clinicians estimate local overall complication rates (pretest probabilities) for the clinically relevant populations in their settings before they apply the predictive properties (likelihood ratios) demonstrated in this study in order to calculate cardiac risks for individual patients (posttest probabilities).

Occupational stress and the professional pilot: the role of the Pilot Advisory Group (PAG)

This paper discusses the role of pilot peer group involvement, using the Pilot Advisory Group (PAG), in assisting pilots who manifest personal problems which derive from occupational and other stressors. Some general aspects of "background" occupational stress are discussed. Attitudes and opinions of professional aviators are identified and their role in denial of symptomatology is developed. The concept of the Pilot Advisory Group (PAG) is then discussed in detail before its role in relation to occupational stress is introduced. While some of the better known problems associated with occupational stress in pilots are mentioned, the emphasis in the paper is on developing new perspectives regarding the identification of stress-induced dysfunction, and also in exploring the suitability of PAG involvement. The formal obligations of management and regulatory authorities are contrasted with what the author sees as the countervailing imperatives of pilot attitudes and beliefs.

Relationship between tissue sensitization and IgE antibody production in rats infected with the nematode, Nippostrongylus brasiliensis

In Nippostrongylus brasiliensis rats, tracheal sensitivity to worm allergens developed prior to intestinal sensitivity and correlated with the early local synthesis of reaginic antibody in the mediastinal (bronchial) lymph nodes. Skin and intestinal sensitivity to worm allergens more nearly correlated with serum reaginic antibody and its synthesis by mesenteric lymph nodes and other tissues. Prostaglandins appeared to modulate intestinal responsiveness to worm allergens. Thus, local reagin synthesis and other microenvironmental factors influence local tissue sensitization and responsiveness to allergens.

Thymic mast cell deficiency in avian muscular dystrophy

In animals with hereditary muscular dystrophy there are thymic abnormalities which may be of etiological significance in the dystrophic process. This study investigated mast cell number and histamine levels in the thymus of normal and dystrophic chickens. For comparison, other lymphoid tissues, namely the spleen and the bursa of Fabricius, and non-lymphoid tissues including the comb and pectoralis major muscle, were similarly studied. Our results show that the thymus of dystrophic adult birds has a deficiency in both mast cell number and histamine content. In the bursa of Fabricius of dystrophic birds a significant elevation in histamine content (microgram/g) was attributed to the abnormally small size of this organ, rather than to an absolute mast cell increase. The deficiency in thymic mast cell number in dystrophic chickens may be significant in the postulated abnormal thymus-muscle interaction of the dystrophic process.

Gut-associated lymphoid tissue in the chicken. I. Morphology, ontogeny, and some functional characteristics of Peyer's patches

Lymphoid aggregates with many of the characteristics of mammalian Peyer's patches (PP) were identified in the chicken intestine. These chicken PP could not be seen with the naked eye at the time of hatching, but by 10 days of age, 1 or 2 PP were identified in 50% of the birds. Up to 16 wk of age, the numbers of PP increased to a maximum of 5 per animal and they were widely scattered in the intestine, apart from one that was regularly found about 5 to 10 cm anterior to the ileocecal junction. As the birds aged, the number of PP declined so that in older birds (58 wk) only a single PP was evident near the ileocecal junction. Chicken PP possess: a distinct lymphoepithelium with M cells and strong pinocytotic activity; follicles and a subepithelium zone and central zone similar to those of the cecal tonsil (CT). Studies with in ovo hormonal bursectomy and age-associated involution of PP suggested that the subepithelial zone is a B-dependent area and the central zone a T, or thymus-dependent region. These observations extend our knowledge of gut-associated lymphoid tissue (GALT) in the bird to include the bursa of Fabricius, CT, PP, and aggregates in the urodeum and proctodeum. They raise issues about the roles of chicken PP that may aid our understanding of the functions of mammalian GALT.

Gut-associated lymphoid tissue in the chicken. I. Morphology, ontogeny, and some functional characteristics of Peyer's patches

Lymphoid aggregates with many of the characteristics of mammalian Peyer's patches (PP) were identified in the chicken intestine. These chicken PP could not be seen with the naked eye at the time of hatching, but by 10 days of age, 1 or 2 PP were identified in 50% of the birds. Up to 16 wk of age, the numbers of PP increased to a maximum of 5 per animal and they were widely scattered in the intestine, apart from one that was regularly found about 5 to 10 cm anterior to the ileocecal junction. As the birds aged, the number of PP declined so that in older birds (58 wk) only a single PP was evident near the ileocecal junction. Chicken PP possess: a distinct lymphoepithelium with M cells and strong pinocytotic activity; follicles and a subepithelium zone and central zone similar to those of the cecal tonsil (CT). Studies with in ovo hormonal bursectomy and age-associated involution of PP suggested that the subepithelial zone is a B-dependent area and the central zone a T, or thymus-dependent region. These observations extend our knowledge of gut-associated lymphoid tissue (GALT) in the bird to include the bursa of Fabricius, CT, PP, and aggregates in the urodeum and proctodeum. They raise issues about the roles of chicken PP that may aid our understanding of the functions of mammalian GALT.

A morphologic study of rabbit bronchial lymphoid aggregates and lymphoepithelium

Ultrastructural studies of the rabbit bronchial mucosa were performed with scanning and transmission electron microscopy. The former revealed that the bronchus-associated lymphoid aggregates could be distinguished from the surrounding tissue, since they were covered with epithelial cells possessing microvilli but not cilia. These lymphoepithelial cells were irregularly placed and provided crevices of varying dimensions at their junctions with other cells. On transmission electron microscopy, these cells showed scanty cytoplasm, several mitochrondria, few other organelles and only rare phagosomes. Just below the epithelium in the lymphoid aggregates, basophil-like cells were seen regularly and were also found in the lymphoepithelium and adjacent normal bronchila epithelium, here lying between cells above the basement membrane. The possible origin of these cells and their potential relationship to lung defense and hypersensitivity disease are discussed.

THYROID ENLARGEMENT PRODUCED BY PROLONGED ADMINISTRATION OF IODINE IN THE MOUSE

Mice were fed diets containing a low level of sodium chloride and 0.2, 1.0, and 5.0 μg iodine per gram respectively for 72 and 142 days. At 142 days, the thyroids weighed 1.6, 3.0, and 4.2 mg per lobe respectively. To determine which thyroid tissue components were responsible for the increase in gland weight, quantitative measurements were performed on histological sections of the thyroid. At the lowest and highest iodine levels, the colloid weights were 1.0 and 3.0 mg per lobe and the epithelium weights were 0.39 and 0.88 mg per lobe respectively. Thus, the change in colloid accounted for 77% and the change in epithelium for 19% of the increase in thyroid weight. Follicular diameter increased by 40%. The goiter induced by iodine proved to be due essentially to an enlargement of follicle size and not to an increase in the number of follicles. Kidney inflammation was observed in animals ingesting large amounts of iodine.

The Plastic Properties of Several Types of Unvulcanized Rubber Stocks at High Rates of Shear

Marzetti, Griffiths, and others have employed the extrusion method for studying the plastic properties of unvulcanized rubber. Some of the results, particularly those of Marzetti, have been very interesting from an academic standpoint. However, none of these experimenters has employed rates of shear differing greatly from those of the compression-type plastometers, which operate at rates much lower than those existing in factory tubing machines. It seemed, then, that this fact might explain why no great discrepancies between extrusion plasticity results and those of the parallel-plate compression-type plastometer were found, at least in so far as could be discovered in the literature. Hence, it was thought desirable, from both an academic and a practical standpoint, to make a study of the flow of rubber through an orifice over a wide range of rates of shear.