A modified algorithm of the single pool urea kinetic model

Urea Kt/V, calculated according to the variable volume single pool urea kinetic model (UKM), has been accepted as the yardstick reflecting the adequacy of haemodialysis therapy. However, the classical algorithm of UKM requires great care in dialyser urea clearance (K) measurement in order to avoid major inaccuracies in estimating the urea distribution volume (V). Thus, we suggest a modified algorithm of UKM which avoids the measurement of K. It assumes an arbitrary V value and then calculates kinetically K as a function of the assumed V value. The rationale of the modified algorithm can be derived from the knowledge that the classical algorithm imposes a proportionality ration between K and V: given a particular set of data, a change in the attributed value of K leads to a proportional change in the calculated V value, so that the ratio K/V remains nearly constant. Aims of the study were (1) to validate the modified algorithm by comparing the resulting Kt/V and normalised protein catabolic rate (NPCR) values with the homologous ones obtained using the classical algorithm in a group of 33 patients on thrice-weekly haemodialysis; plasma water urea concentrations were used with the classical algorithm (CApw) and the modified algorithm (MApw); and (2) to verify the possibility of using plasma urea concentrations with the modified algorithm (MAp) instead of the more rigorous plasma water concentrations. NPCR (g/kg per day) was 1.33 +/- 0.05 in CApw, 1.29 +/- 0.05 in MApw and 1.28 +/- 0.04 in MAp. Kt/V was 1.27 +/- 0.03 in CApw, 1.25 +/- 0.03 in MApw and 1.26 +/- 0.03 in MAp.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between knowledge about acquired immunodeficiency syndrome and the implementation of universal precautions by registered nurses

The relationship between the level of knowledge of registered nurses (RNs) concerning acquired immunodeficiency syndrome (AIDS)-related issues and the practical observance of universal precautions was studied. It was hypothesized that the more knowledge a nurse has concerning AIDS the more likely he or she is to implement universal precautions. All registered nurses who have direct patient contact (N = 400) and are employed at a Northeastern teaching medical center, were provided a packet of three questionnaires and encouraged to participate. Two hundred thirteen (53%) RNs returned completed questionnaires. Subgroups were examined for trends relating such parameters as age and the amount of AIDS knowledge, using analysis of variance. The major hypothesis was tested by correlating the overall scores for AIDS knowledge and the implementation score. Results indicated no relationship between knowledge and the implementation of universal precautions (r = -0.12). When evaluating scores according to work areas, those subjects with higher knowledge scores had lower practice scores. Other demographic variables showed no influence on either knowledge or implementation scores as measured by this study. Further study is needed to understand what factors will motivate RNs to implement universal precautions.

Amniotic fluid embolism associated with castor oil ingestion

We report a case of an amniotic fluid embolism (AFE) causing a cardiorespiratory arrest associated temporally with ingestion of castor oil in a full-term normal pregnancy. Risk factors usually associated with AFE were not found in this patient.

Estrogenic effect of phenol red in MCF-7 cells is achieved through activation of estrogen receptor by interacting with a site distinct from the steroid binding site

MCF-7 cells serially subcultured in media containing phenol red show poor stimulation of progesterone receptor (PR) synthesis in response to estradiol compared to cells grown in phenol red-free media. Phenol red, when added to cytosol, did not compete with [3H]estradiol for estrogen binding sites in concentrations ranging from 2 microM-1 mM. However 25 microM of the dye was sufficient to increase nuclear translocation of estrogen receptor (ER) in the intact cell. Phenol red activates cytoplasmic ER as indicated by DNA-cellulose binding studies. When cells grown in phenol red-free medium were exposed to phenol red for 48 h, PR levels increased in a dose dependent manner. From these data, it may be concluded that phenol red causes estrogenic effect in MCF-7 cells through activation of cytoplasmic receptor by interacting at a site distinct from the steroid binding site.

Are estrogen receptors cytoplasmic or nuclear? Some immunocytochemical and biochemical studies

The subcellular localization of estradiol receptor (ER) has been examined using various experimental approaches. Immunocytochemical studies using the monoclonal antibody JS 34/32, raised against calf uterine cytosolic ER, yielded only equivocal results. In general, cells and tissues pretreated with estradiol showed positive immunostaining in the nuclei whereas those not exposed to the steroid did not show any staining. Nuclear translocation of ER was examined in intact MCF-7 cells using compounds which are known to influence receptor activation. When MCF-7 cells were exposed to molybdate (20 mM), nuclear translocation was completely inhibited while dithiothreitol (20 mM), dibutyryl cAMP (1 microM) and dibutyryl cGMP (1 microM) increased the translocation 2-3-fold. Phenol red, at the range of concentrations generally used in tissue culture media, also increased translocation. The physiological validity of such translocation was examined using cellular progesterone receptor (PR) synthesis as a specific parameter. When MCF-7 cells were grown in media containing phenol red for 48 h, the PR synthesis increased significantly. We further examined whether cytoskeletal proteins are involved in the translocation of ER. Colchicine, an inhibitor of microtubule assembly, inhibited translocation of ER in MCF-7 cells at 1-10 microM. PR synthesis was also inhibited by colchicine in a dose-dependent manner. It may be concluded from these and other published data that ER may not be located at all times in a single subcellular compartment but may rather exist in a dynamic equilibrium between the plasma membrane, cytoplasm and nucleus.

Effects of exercise on the biochemical aging of mammalian myocardium. II. Creatine phosphokinase

Male Fischer 344 rats from a long inbred colony (by brother-sister mating) were subjected to moderate (forced swimming) physical activity on a regular basis, beginning at 3 weeks following weaning. Normally caged, sedentary littermates were employed as controls at each age level. Exercised animals showed a greater total ventricular mass and correspondingly lower body weight, and the heart to body weight ratio for experimental animals about 25% higher at all ages, beginning at 3 months following onset of exercise. Finally, the specific activity of myocardial creatine phosphokinase was consistently higher for the exercised animals, beginning at 3 months of age and through 16 months of such exercise. These data support previous findings from this laboratory, as well as by others, that long-term moderate exercise begun early in life has a continuing, beneficial effect on the mammalian heart, both at the gross functional and intracellular biochemical levels.

Effects of exercise on the biochemical aging of mammalian myocardium. I. Actomyosin ATPase

Male Fischer 344 rats were subjected to regular forced exercise beginning at weaning and continued until sacrificed at ages ranging from 2 to 18 months. Littermates served as sedentary controls. At all ages examined, the exercised animals had greater heart and lower body weights. Actomyosin was isolated from the myocardium and the ATPase activity of the contractile protein preparation was measured. Only the sedentary animals exhibited an age-related loss in enzyme activity. The physically trained animals had substantially higher ATPase specific activity than the controls at all ages. This difference in ATPase specific activity may be the result of the synthesis of different isozymic forms of myosin or changes in the regulatory proteins of actomyosin (tropomyosin and troponin). It is suggested that lifelong regular exercise may alter the known biochemical changes in the heart muscle that relate to declining cardiac function.

Age-related activity changes in actomyosin ATPase and arginine phosphokinase in male Drosophila melanogaster Meig

The specific activity of each of the two enzymes primarily concerned with the energy metabolism of flight muscle contraction was determined in male Drosophila melanogaster, from emergence through 5 weeks postemergence. Ca++-activated actomyosin ATPase activity rose rapidly from a minimum at emergence to a peak level at 4-5 days, falling gradually thereafter to a minimum level at 10-11 days postemergence, with no change thereafter. Arginine phosphokinase activity rose more gradually to a maximum at 11-12 days postemergence and then fell slowly to a minimum at 18-19 days. These data represent a sequential pattern of biochemical changes similar to those previously observed in other dipteran species, confirming the primary role of a genetic program for maturation and senescence of flight ability in holometabolous adult insects at the functional and underlying cellular, biochemical levels.

Changes with age of myocardial creatine phosphokinase in the male Fischer rat

Myocardial creatine phosphokinase (CPK) was extracted from crushed tissue in 0.01 M Tris buffer at pH 9.0 and purified by successive ammonium chloride and ethanol precipitations. The CPK activity was estimated by measuring the rate of phosphocreatine formation by the transphosphorylation of creatine by ATP. There was a slight rise in CPK activity from 1 to 2 months of age. Thereafter, there was a progressive fall in the CPK activity of 14% by 7-9 months of age, 20% by about one year of age, and 25% by 16-24 months of age. These data indicate that, with advancing age, there is an inability to rapidly restore adequate cellular levels of the high-energy substrate ATP during muscular contraction. Since the loss with age of myocardial CPK parallels a strong biochemical correlate for known declining cardiac function in aging mammals, including man.

Calcium sensitivity of myocardial actomyosin ATPase in young and mature male Fischer rats. A brief note

Although myocardial actomyosin ATPase specific activity determined at Ca2+ levels of 1 x 10(-3) to 1 x 10(-2) M is consistently higher in two-month old male Fischer rats than in twelve-month old individuals, this difference can be eliminated if the enzyme is assayed at lower calcium concentrations. This suggests that the previously reported, declining actomyosin ATPase activity in the rat myocardium with advancing age may represent an age-related diminished ability of calcium to reverse the known inhibition upon actomyosin ATPase by the regulatory proteins.

Bone densitometry with L125 in the study of uraemic osteropathy: semeiological signifiance and limitations

Bone densitometry using I125 is a very easy method of investigation; it may be used repeatedly and simultaneously at different bone levels without distress to patients. The problems involved were those of the value, semeiological significance and possible limitations of this method in the investigation of uraemic osteopathy. These problems were solved successfully in tests carried out on 87 patients of both sexes suffering from various degrees of chronic nephropathy and on chronic haemodialysis patients. The method is reliable: reproducibility tests in normal and uraemic subjects were satisfactory; the indexes remain constant, usually in normal subjects. The parameters are "Bone Mineral Content" and "Bone Index". Trabecular bone is more sensitive than cortical bone, although comparisons between the two types of bone produce interesting data. There are difference dependent on sex. The method which is more sensitive than others enables: 1) Normal and nephropathic subjects, to be distinguished from one another. The latter generally show a lower mineral content and bone index (clinical picture of osteomalacia, osteoporosis, hyperparathyroidism) seldom a higher or a normal one. 2) The same bone sites to be examined over a given period. 3) Treatment of patients to be monitored.

Function of the kidney in adult patients with Cooley's disease. A preliminary report

The function of the kidney in adult subjects with Cooley's disease has been hitherto inadequately investigated. In 10 patients suffering from thalassemia major, glomerular filtration rate, renal plasma flow, renal blood flow have been studied, together with urine concentration capacity. The authors emphasize certain pathological changes, such as the increase in renal plasma flow and the failure of the urine concentration ability. On the basis of renal biopsies, two pathogenetic theories are discussed: the functional impairment of the coutercurrent system and fibrosis of the medullary tissue.