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Biomedical subjects

A Spitzer

Publications and source records attributed to A Spitzer.

At least 19 recordsLinked to original sources
PubMed2001

Ontogeny of renal phosphate transport and the process of growth.

The kidneys of infants and children reabsorb a high fraction of the filtered phosphate (Pi), as appropriate to the needs of a growing organism. This high Pi reabsorptive rate is associated with a high capacity (Vmax) of the Na+-Pi symport system. At the molecular level this high reabsorptive capacity appears to be due to the presence of a growth-specific Na-Pi cotransporter. Several experimental findings support this assumption. Firstly, the expression of NaPi-2 mRNA is, if anything, lower in the renal cortex of young animals than of adult animals. Secondly, polyA RNA obtained from growing animals depleted of NaPi-2 by specific hybridization with an antisense 16-mer induces Na+-Pi transport in oocytes. No induction of Na+-Pi transport was observed in oocytes injected with hybridized polyA RNA obtained from adult animals. Thirdly, polyA RNA derived from young rats, depleted of NaPi-2 by subtractive hybridization with adult animal renal cortical cDNA, retains its ability to encode for Na+-Pi cotransport in oocytes. Adult animal renal cortical polyA RNA, depleted of NaPi-2 by subtractive hybridization, failed to induce Na+-Pi uptake into oocytes. Fourthly, renal cortical polyA RNA from young animals, depleted of NaPi-2, contains a region that is highly homologous (80%-92%) with the corresponding region of other modulated NaPi (type II) transporters. Fifthly, this region is also present in the polyA RNA obtained from the renal cortex of newborn rats (1st week of life), despite the fact that NaPi-2 is absent at this early age. Lastly, Npt2 (-/-) knockout mice, although hypophosphatemic and phosphaturic, filter and reabsorb Pi at rates exceeding those that can be accounted for by the expression of type I and III transporters. Based on these observations it is reasonable to surmise that the high Vmax of the Na+-Pi cotransport system observed in the young is due to a large extent to the presence of a growth-specific NaPi transporter, homologous but not identical to already cloned type II NaPi transporters.

Absorption↗
PubMed2001

Israeli nurses' knowledge of health care reforms.

OBJECTIVES: This study examines health care reforms' implementation processes from the perspective of nurses' knowledge regarding the reforms. The research has been carried out in the Israeli context, where health care reforms were initiated in 1995. Three specific research questions were formulated: (a) What is the level of nurses' knowledge regarding the recommendations of the Netanyahu committee? (b) What is the level of nurses' knowledge concerning the basic principals of the National Insurance Law? and (c) Are there knowledge differences relating to employment setting (hospital, community, and educational settings), nurses' roles (managerial vs. staff nurses), years of experience, and level and type of education? METHOD: The stratified nonproportional random sample consisted of a total of 468 nurses. Of these nurses, 206 were employed in community settings (136 in curative care, and 70 in preventive care), 137 were employed in hospital settings, and 125 worked in schools and departments of nursing. Research tools, developed for the purpose of this study, included the nurses' knowledge questionnaire comprised of five subscales, and the knowledge relevancy questionnaire. RESULTS: Overall, data demonstrated a low to moderate level of knowledge on all knowledge scales. Knowledge level on the criteria questions was particularly low. Contrary to the low level of knowledge, nurses regarded health care reforms' knowledge as highly relevant to their work life. Curative setting, an extensive work experience, managerial position, and non-nursing academic degree were all positively related to higher levels of reforms' knowledge. CONCLUSION: These findings should encourage both policy makers and managers in various health care organizations to develop programs for informing health care providers on central aspects of health care reforms considered most relevant to the practice setting.

Adult↗
PubMed2001

Phosphate depletion in opossum kidney cells: apical but not basolateral or transepithelial adaptions of Pi transport.

Monolayers of opossum kidney (OK) cells are widely used as models for the renal proximal tubule. OK cells adapt to phosphate (Pi) depletion by increasing their capacity for apical and basolateral Na+-dependent Pi uptake. Because NMR-visible cell Pi was found to be decreased in Pi-deprived kidney cells, we suggested that up-regulation of basolateral Pi efflux also occurs during adaptation to Pi deprivation [American Journal of Physiol 1994;267:C915-919]. In order to test this hypothesis, we measured the cell Pi pool, basolateral Pi efflux and transepithelial Pi fluxes in OK cells grown on permeable plastic filters, exposed overnight to solutions containing either 0.5 mM (deprived) or 2.0 mM (replete) Pi or 32Pi. Following steady state or acute loading with 32Pi, the specific activity (SA) of cell Pi, the cell Pi pool and the basolateral efflux of 32Pi were measured. In the steady state, a 2-fold increase in Pi uptake sustained the intracellular Pi pool at 85% of the control level (30 +/- 5 nmol/mg) in spite of a decrease in extracellular Pi from 2 to 0.5 mM. When the extracellular Pi was acutely (1 h) reduced to 0.1 mM, the cell Pi pool decreased (to 3 +/- 1 nmol/mg) both in cells previously adapted overnight to either 0.5 or to 2 mM Pi (p >0.3). The rates of absolute and fractional basolateral washout of cell 32Pi after 1 h loading with 0.1 mM 32Pi were similar in cells adapted to 0.5 compared to 2 mM Pi. This indicates that Pi depletion did not affect the effective permeability of the basolateral membranes to Pi. Adaptation for 16 h to 0.5 compared to 2 mM Pi did not alter the rate of net transepithelial transport of 0.1 mM Pi from the apical to the basal compartment but reduced (p < 0.05) the unidirectional fluxes of both 32Pi and 14C-mannitol. An insufficient driving force (unchanged or low Pi concentration in the transport pool, low electrical or coupled-anion gradients) and a constant effective basolateral Pi permeability must have limited basolateral Pi efflux in cells exposed to 0.1 mM Pi. Thus, in OK cells grown on plastic support there are no adaptive increases in either basolateral Pi efflux, or in transcellular and paracellular Pi transport, in response to Pi depletion. Adaptations are limited to increases in apical and basolateral sodium-dependent Pi uptakes that can maintain the cell Pi pool as long as apical Pi is not too low (> or =0.5 mM). The OK cells adapt to low Pi concentrations conserving cell Pi but not increasing basolateral Pi efflux nor transepithelial Pi transport.

Adaptation, Physiological↗
PubMed2000

Activating mineralocorticoid receptor mutation in hypertension exacerbated by pregnancy.

Hypertension and pregnancy-related hypertension are major public health problems of largely unknown causes. We describe a mutation in the mineralocorticoid receptor (MR), S810L, that causes early-onset hypertension that is markedly exacerbated in pregnancy. This mutation results in constitutive MR activity and alters receptor specificity, with progesterone and other steroids lacking 21-hydroxyl groups, normally MR antagonists, becoming potent agonists. Structural and biochemical studies indicate that the mutation results in the gain of a van der Waals interaction between helix 5 and helix 3 that substitutes for interaction of the steroid 21-hydroxyl group with helix 3 in the wild-type receptor. This helix 5-helix 3 interaction is highly conserved among diverse nuclear hormone receptors, suggesting its general role in receptor activation.

Adolescent↗
PubMed2000

Hormonal regulation of sodium-dependent phosphate transport in opossum kidney cells.

There are multiple regulators of renal proximal tubule sodium-dependent phosphate (Na(+)-Pi) transport, including 1,25-dihydroxyvitamin D (1,25-Vit. D), parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1), and arachidonic acid (AA) and/or its metabolites. The purpose of our studies was to determine whether the effect of these factors on Pi transport is synergistic or antagonistic. The control solution or the substances were added independently or coincidentally to opossum kidney (OK) cells before incubation for 4 h. 1,25-Vit. D (10(-8) M) had no significant effect on Pi transport ( upward arrow6.8%; p = 0.8). PTH (10(-7) M) significantly inhibited Pi transport by 39.6% (p < 0.0001). IGF-1 (10(-8) M) stimulated Pi transport by 19.6% (p < 0.0001). The AA metabolite 20-HETE (10(-7) M) had no significant impact on Pi transport ( downward arrow6.4; p = 0.3). The combined effect of 1,25-Vit. D and PTH was no different from PTH alone (p = 0.2). Likewise, addition of either 1,25-Vit. D or 20-HETE to IGF-1 failed to affect the magnitude of the increase on Pi transport induced by IGF-1 alone (p = 0.4, p = 0.6, respectively). The combination of 20-HETE and PTH was not different from that observed with PTH alone (p = 0.9). We conclude that in OK cells, PTH inhibits whereas IGF-1 stimulates Pi transport into OK cells. The effects of each of these hormones are independent and unaffected by either 1,25-Vit. D or 20-HETE.

Animals↗
PubMed1999

The need and ability to achieve cognitive structuring: individual differences that moderate the effect of stress on information processing.

The authors examined the hypothesis that the interaction between the need for cognitive structure (NCS) and the ability to achieve cognitive structure (AACS) moderates the effect of stress on information processing. NCS is the preference for using cognitive structuring, as opposed to piecemeal processes, as a means to achieve certainty. AACS is the extent to which individuals are able to apply information processes that are consistent with their levels of NCS. The hypothesis was validated in 4 studies, which showed that stress increased high-AACS participants' use of cognitive structuring if they had high NCS and reduced it if they had low NCS. An opposite effect was found for low-AACS participants. The implications of these results for the understanding of the mechanisms responsible for the effect of stress on information processing are discussed.

Achievement↗
PubMed1999

Evaluation of an innovative curriculum: nursing education in the next century.

The present research focused on an interim evaluation of a new nursing curriculum made by first- and second-year undergraduates. Study 1 examined the assessments made by 90 students of the new, actual programme of their studies, as well as an ideal one, on 21 bipolar criteria reflecting the developing changes in health care practices and higher educational processes in western society. The results of study 1 indicated that students perceived the actual programme as compatible with health care changes, but lacking in terms of the learning process. Study 2 investigated the same assessments among 105 registered nurses who evaluated the traditional nursing programme under which they were trained as well as an ideal one. The results of study 2 showed that registered nurses perceived past curricula as lower than the ideal on both health care and process of learning. The results of this interim evaluation imply that the new nursing curriculum follows health care trends, but a shift in the educational process is required.

Adolescent↗
PubMed1999

Multiple arachidonic acid metabolites inhibit sodium-dependent phosphate transport in OK cells.

The cytochrome P450-dependent monoxygenase pathway represents a major route for the metabolism of arachidonic acid (AA) in the kidney. In turn, AA metabolites have been shown to affect renal electrolyte metabolism, including sodium transport. Specifically AA, 20-HETE and 12-HETE inhibit sodium-dependent (Na+-Pi) uptake into renal culture cells, and both 12-HETE and 14,15 EET have been shown to reduce renin release from renal cortical slices. Since the bulk of Pi transport occurs in the proximal tubule (PT), and the PT is a major site of AA metabolism, we studied the effect of AA and several of its metabolites on Na+-Pi uptake into PT-like opossum kidney (OK) cells. Incubation of OK cells in AA (10(-8) M) resulted in 17% inhibition of Pi uptake. Three metabolites of omega-hydroxylation of AA induced significant decreases in Pi uptake: 19R-HETE (10(-8) M) by 36% (P=0.008), 19S-HETE (10(-8) M) by 24% (P=0.002) and 20-COOH-AA (10(-8) M), a metabolite of 20-HETE, by 25% (P<0.0001). 14,15 EET (10(-8) M), a breakdown product of AA by the epoxygenase pathway, had the greatest effect on Pi uptake in OK cells. It decreased Pi uptake by 47% (P < 0.0001). Addition of the P450 inhibitor, 7-ER (10(-8) M), to OK cells resulted in a significant stimulation (28%) of Pi uptake (P=0.016). These results indicate that these AA metabolites have a significant inhibitory effect on Na+-Pi uptake in OK cells.

8,11,14-Eicosatrienoic Acid↗
PubMed1999

[The assessment of sudomotor function for diagnosis of autonomic diseases. Principles and methods].

Thermoregulatory and emotional sweating can be distinguished in humans. While the first is organized via feed back mechanisms involving thermoreceptors, thermoregulatory centers in the brain and the effector system (sympathetic nervous system and sweat glands), the latter is generated directly by cortical and limbic mechanisms without any feed back. Sweat glands on the hairy skin can be stimulated by thermoregulatory mechanisms (rising body temperature), the emotional sweating on the glabrous skin as a result of an arousal reaction and they can be stimulated by peripheral acting cholinergic agents, which initiate direct or axon reflex mediated sweating. To evaluate sweating there are qualitative methods that visualize the sweat response or indirect methods like the registration of skin potentials. Alternatively sweat output can be quantified by evaporative measurement. For best results these methods should be combined. In this way autonomic dysfunction e.g. after nerve lesions, in polyneuropathies, central lesions and certain pain disorders can be assessed. The sudomotor function tests complete the conventional electrophysiological methods.

Animals↗
PubMed1999

The effect on coping of monitoring, blunting, and the ability to achieve cognitive structure.

The effects of monitoring and blunting on individuals' choices of coping strategies and their effectiveness were examined. In addition, the authors explored the effect of the ability to achieve cognitive structure (AACS), defined as either or both of the following: (a) the ability to avoid information that either cannot be categorized or clashes with the individual's existing knowledge; (b) the ability to organize knowledge to fit an already existing cognitive structure. The results showed that in addition to the main effects of monitoring on problem-focused coping and social support seeking behaviors and of blunting on the use of wishful thinking, AACS was found to moderate blunting's influence on problem-focused coping as well as the effectiveness of distancing and avoidance coping. Finally, the results showed that the combination of high monitoring and high blunting sometimes contributes to coping effectiveness.

Adaptation, Psychological↗
PubMed1999

Cardiac sympathetic denervation in early stages of amyotrophic lateral sclerosis demonstrated by 123I-MIBG-SPECT.

Involvement of the autonomic cardiac nervous system in early stages of amyotrophic lateral sclerosis (ALS) was evaluated in 40 patients. I-123-metaiodobenzylguanidine-single photon emission computed tomography (MIBG-SPECT) and heart rate variability (HRV) yielded information about sympathetic and parasympathetic innervation of the heart. MIBG-SPECT is a sensitive diagnostic method for demonstration of early cardiac sympathetic denervation. Both sympathetic and parasympathetic dysfunction was observed in 16 (40%) out of 40 patients. Mean cardiac MIBG uptake as demonstrated by the heart/mediastinum ratio was significantly reduced in all ALS patients in comparison with controls (P<0.01). The global MIBG-SPECT score was clearly abnormal in 29% and slightly abnormal in 22% of patients. HRV was diminished in 6 of 38 patients, 4 of whom having an abnormal MIBG-SPECT score as well. The presented results indicate that ALS patients with mild to moderate impairment may have evidence of postganglionic sympathetic adrenergic cardiac or cardiovagal denervation. To our knowledge, this is the first study indicating possible postganglionic sympathetic denervation in ALS. The original concept of ALS as an isolated degeneration of motor neurons seems to extend to a more widespread understanding of the disease which possibly represents different entities.

3-Iodobenzylguanidine↗
PubMed1998

The NMDA receptor antagonist amantadine reduces surgical neuropathic pain in cancer patients: a double blind, randomized, placebo controlled trial.

Neuropathic pain is often severe, persistent, and responds poorly to analgesic medications. Recent evidence suggests that N-methyl-D-aspartate (NMDA) receptor antagonists may be effective in the treatment of neuropathic pain. The present trial was designed to test the efficacy of acute administration of the NMDA receptor antagonist amantadine in relieving surgical neuropathic pain in patients with cancer. The study sample consisted of 15 cancer patients with the diagnosis of surgical neuropathic pain. Two 500 ml infusions of either 200 mg amantadine or placebo were administered over a 3 h period, in a randomized order, 1 week apart from each other. Spontaneous and evoked pain were measured for 48 h before treatment, during treatment, and for 48 h following treatment. An average pain reduction of 85% was recorded at the end of amantadine infusion vs. 45% following placebo administration. The difference in pain relief between the two treatments was statistically significant (P = 0.009). Mean pain intensity remained significantly lower during the 48 h following amantadine treatment as compared with the 48 h prior to treatment (31% reduction; P = 0.006), whereas no such effect was found with the placebo (6% reduction; P = 0.40). Amantadine, but not the placebo, also reduced 'wind up' like pain (caused by repeated pinpricking) in four patients. We conclude that amantadine infusion is a safe and effective acute treatment for surgical neuropathic pain in cancer patients. Further trials with long-term oral or parenteral amantadine treatment should be conducted.

Adult↗
PubMed1998

20-HETE mediates the effect of parathyroid hormone and protein kinase C on renal phosphate transport.

Parathyroid hormone (PTH) is a major inhibitor of renal proximal tubule (PT) sodium-dependent phosphate (Na+-Pi) cotransport. PTH is thought to exert its effect on Pi transport in the PT via the protein kinase A (PKA) and C (PKC) intracellular signalling pathways. PKC-dependent phosphorylation of phospholipase A2 stimulates arachidonic acid (AA) release, the latter a potent inhibitor of Pi transport. In turn, AA is metabolized to 20-hydroxyeicosatetraenoic acid (20-HETE) in the PT. In addition, 20-HETE production is stimulated by PTH. We therefore explored the possibility that 20-HETE may mediate the PTH/PKC inhibition of renal Na+-Pi cotransport. To this end, we tested the effect of 20-HETE on Na+-Pi cotransport in proximal tubule-like cells. Exposure of opossum kidney (OK) cells for 4 h to 20-HETE (10(-7) M) decreased Na+-dependent uptake of 32Pi (from 0.26 +/- 0.02 to 0.19 +/- 0.01 nmol/mg protein.min) by approximately 25% (P < 0.001). The inhibition was due to a reduction in Vmax. 20-HETE had no significant effect on either the apical amiloride-sensitive and insensitive 22Na uptakes or on basolateral ouabain-sensitive 86Rb uptake, and was specific for Pi. These results indicate that 20-HETE specifically inhibits Na+-dependent Pi transport in OK cells and that it may be a mediator of PTH action in the PT.

Animals↗
PubMed1998

Moving into the information era: does the current nursing paradigm still hold?

The transition into the information era is characterized by society's passage through three crossroads representing a change from: (a) technology to post-technology; (b) rigid jobs and hierarchies to dejobbing and vanishing hierarchies; and (c) limited competition to competition dominating all markets. These transitions have caused dramatic changes in the health care system at large and escalating problems that cannot be solved within the current paradigm of nursing. Among the nursing problems that were identified are those including difficulties in: (a) defining the relative contribution of nursing vis a vis other health professions; (b) the scope and dimensions of nursing authority; (c) implementing all aspects of the nursing intervention; (d) actualizing caring in nursing intervention; and (f) implementing the nursing process as a major thinking process in the profession. The analysis of the state of nursing suggests that the current clinical paradigm fails to consolidate the economic and quality issues into the core of nursing. It is not capable of solving central professional problems and emerging dilemmas. Considering that under the current paradigm, nursing has difficulties in highlighting to clients and the system alike where nursing can make a difference, it is questionable whether such a paradigm can ensure the existence of nursing in the future.

Health Transition↗
PubMed1998

Nursing in the health care system of the postmodern world: crossroads, paradoxes and complexity.

Entering the postmodern world in which society is confronting crossroads, paradoxes, and complexity, the health care system is encountering a transformation more comprehensive and revolutionary than has ever been seen before. Analysis of the state of nursing vis a vis these transformations indicates that the current paradigm does not ensure the existence of the profession in the postmodern health care system. That is because of increased difficulties in consolidating the economic and quality issues into the core of nursing, and in understanding the complexity inherent in health related situations.

Health Care Reform↗
PubMed1998

Sudden infant death syndrome rates subsequent to the American Academy of Pediatrics supine sleep position.

OBJECTIVES: In April 1992, the American Academy of Pediatrics (AAP) recommended that healthy infants be positioned for sleep on their side or back to reduce the risk of Sudden Infant Death Syndrome (SIDS). The authors hypothesized three different forms of the intervention to examine the impact of the recommendation according to theory such as technology diffusion. Seasonality was included in the models to control its effect when testing. METHODS: Box and Tiao time-series intervention methodology was used to examine the effect of the AAP recommendation on SIDS rates. Sudden Infant Death Syndrome mortality data from Philadelphia and Chicago were examined separately for white and nonwhite populations over 32 quarters. RESULTS: Overall SIDS rates dropped significantly according to an abrupt effect from the intervention. However, the effect appeared to be gradually declining in Philadelphia but permanent in Chicago. In Philadelphia, a decline of 62.3% was estimated in whites in the first quarter after the intervention but decreased to only 5% in the last quarter of 1994. A decline of 35.8% was estimated in nonwhites in the first quarter after the intervention but decreased to only 9.4% in the last quarter of 1994. An abrupt and permanent decrease of 26.7% and 16.5% was found in Chicago for whites and nonwhites, respectively. CONCLUSIONS: Evidence of an abrupt adoption of the recommendation can be explained by the authority innovation decision made by the AAP. Some evidence was found that the effect is temporary, perhaps because physicians are reversing earlier decisions. The demonstrated methodology provides a powerful way to test naturally occurring interventions from quasiexperimental designs to test the impact of policy guidelines.

Chicago↗
PubMed1997

[Iodine content of Bavarian consumer milk].

Over a period of one year the iodine content of the milk of 28 bavarian dairies was determined monthly by a gaschromatographical method. The annual mean value was 115 micrograms/l. In March, April and November, December, respectively a distinct increase of the concentration was observed. In the southern part of Bavaria the iodine contents were below 100 micrograms/l in contrast to the region Oberpfalz and Franken where contents up to 150 micrograms/l could be determined. Compared with concentrations in different tables the iodine content in bavarian milk could increase the iodine uptake up to 6%.

Adolescent↗