Can a Low-Phosphate Diet for Chronic Kidney Disease Treat Cancer? An Interdisciplinary Literature Review

Background: Cancer therapeutics have a low success rate in clinical trials. An interdisciplinary approach is needed to translate basic, clinical, and remote fields of research knowledge into novel cancer treatments. Recent research has identified high dietary phosphate intake as a risk factor associated with cancer incidence. A model of tumor dynamics predicted that reducing phosphate levels sequestered in the tumor microenvironment could substantially reduce tumor size. Coincidently, a low-phosphate diet is already in use to help patients with chronic kidney disease manage high serum phosphate levels. Methods: A grounded-theory literature-review method was used to synthesize interdisciplinary findings from the basic and clinical sciences, including oncology, nephrology, nutritional epidemiology, and dietetic research on cancer. Results: Findings of tumor remission associated with fasting and a ketogenic diet, which lower intake of dietary phosphate, support the hypothesis that a low-phosphate diet will reduce levels of phosphate sequestered in the tumor microenvironment and reduce tumor size. Additionally, long-term effects of a low-phosphate diet may reverse dysregulated phosphate metabolism associated with tumorigenesis and prevent cancer recurrence. Conclusions: Evidence in this article provides the rationale to test a low-phosphate diet as a dietary intervention to reduce tumor size and lower risk of cancer recurrence.

Myopia, Sodium Chloride, and Vitreous Fluid Imbalance: A Nutritional Epidemiology Perspective

Theories of myopia etiology based on near work and lack of outdoor exposure have had inconsistent support and have not prevented the rising prevalence of global myopia. New scientific theories in the cause and prevention of myopia are needed. Myopia prevalence is low in native people consuming traditional diets lacking in sodium chloride, and nutritional epidemiological evidence supports the association of rising myopia prevalence with dietary sodium intake. East Asian populations have among the highest rates of myopia associated with high dietary sodium. Similar associations of sodium and rising myopia prevalence were observed in the United States in the late 20th century. The present perspective synthesizes nutritional epidemiology evidence with pathophysiological concepts and proposes that axial myopia occurs from increased fluid retention in the vitreous of the eye, induced by dietary sodium chloride intake. Salt disturbs ionic permeability of retinal membranes, increases the osmotic gradient flow of fluid into the vitreous, and stretches ocular tissue during axial elongation. Based on the present nutritional epidemiology evidence, experimental research should investigate the effect of sodium chloride as the cause of myopia, and clinical research should test a very low-salt diet in myopia correction and prevention.

Breast cancer, alcohol, and phosphate toxicity

Alcohol consumption is associated with an increased risk of breast cancer, even at low alcohol intake levels, but public awareness of the breast cancer risk associated with alcohol intake is low. Furthermore, the causative mechanisms underlying alcohol's association with breast cancer are unknown. The present theoretical paper uses a modified grounded theory method to review the research literature and propose that alcohol's association with breast cancer is mediated by phosphate toxicity, the accumulation of excess inorganic phosphate in body tissue. Serum levels of inorganic phosphate are regulated through a network of hormones released from the bone, kidneys, parathyroid glands, and intestines. Alcohol burdens renal function, which may disturb the regulation of inorganic phosphate, impair phosphate excretion, and increase phosphate toxicity. In addition to causing cellular dehydration, alcohol is an etiologic factor in nontraumatic rhabdomyolysis, which ruptures cell membranes and releases inorganic phosphate into the serum, leading to hyperphosphatemia. Phosphate toxicity is also associated with tumorigenesis, as high levels of inorganic phosphate within the tumor microenvironment activate cell signaling pathways and promote cancer cell growth. Furthermore, phosphate toxicity potentially links cancer and kidney disease in onco-nephrology. Insights into the mediating role of phosphate toxicity may lead to future research and interventions that raise public health awareness of breast cancer risk and alcohol consumption.

Breast Cancer and Bone Mineral Density in a U.S. Cohort of Middle-Aged Women: Associations with Phosphate Toxicity

Breast cancer is associated with phosphate toxicity, the toxic effect from dysregulated phosphate metabolism that can stimulate tumorigenesis. Phosphate toxicity and dysregulated phosphate metabolism are also associated with bone mineral abnormalities, including excessive bone mineral loss and deposition. Based on shared associations with dysregulated phosphate metabolism and phosphate toxicity, a hypothesis proposed in the present mixed methods-grounded theory study posits that middle-aged women with incidence of breast cancer had a greater magnitude of changes in bone mineral density over time compared with women who remained cancer-free. To test this hypothesis, a mixed-effects model was used to analyze the associations of breast cancer incidence with spinal bone mineral density changes in the U.S. Study of Women's Health Across the Nation. Compared with women in the cohort who remained cancer-free, women who self-reported breast cancer had higher bone mineral density at baseline, but had more rapid losses in bone mineral density during follow-up visits. These findings agree with the hypothesis that a greater magnitude of changes in bone mineral density over time is associated with breast cancer in a cohort of middle-aged women. The findings also have implications for studies investigating dysregulated phosphate metabolism and phosphate toxicity as causative factors of bone metastasis in metastatic breast cancer. Additionally, the authors previously found increased breast cancer risk associated with high dietary phosphate intake in the same cohort of middle-aged women, and more studies should investigate a low-phosphorus diet to reduce bone mineral abnormalities and tumorigenesis in breast cancer patients.

High Dietary Phosphorus Is Associated with Increased Breast Cancer Risk in a U.S. Cohort of Middle-Aged Women

Research has shown that high amounts of dietary phosphorus that are twice the amount of the U.S. dietary reference intake of 700 mg for adults are associated with all-cause mortality, phosphate toxicity, and tumorigenesis. The present nested case-control study measured the relative risk of self-reported breast cancer associated with dietary phosphate intake over 10 annual visits in a cohort of middle-aged U.S. women from the Study of Women's Health Across the Nation. Analyzing data from food frequency questionnaires, the highest level of daily dietary phosphorus intake, >1800 mg of phosphorus, was approximately equivalent to the dietary phosphorus levels in menus promoted by the United States Department of Agriculture. After adjusting for participants' energy intake, this level of dietary phosphorus was associated with a 2.3-fold increased risk of breast cancer incidence compared to the reference dietary phosphorus level of 800 to 1000 mg, which is based on recommendations from the U.S. National Kidney Foundation, (RR: 2.30, 95% CI: 0.94-5.61, p = 0.07). Despite the lack of statistical significance, likely due to the small sample size of the cohort, the present nested case-control study's clinically significant effect size, dose-response, temporality, specificity, biological plausibility, consistency, coherence, and analogy with other research findings meet the criteria for inferred causality in observational studies, warranting further investigations. Furthermore, these findings suggest that a low-phosphate diet should be tested on patients with breast cancer.

Salt-Sensitive Hypertension: Mediation by Salt-Induced Hypervolemia and Phosphate-Induced Vascular Calcification

Preventing hypertension by restricting dietary salt intake, sodium chloride, is well established in public health policy, but a pathophysiological mechanism has yet to explain the controversial clinical finding that some individuals have a greater risk of hypertension from exposure to salt intake, termed salt-sensitive hypertension. The present perspective paper synthesizes interdisciplinary findings from the research literature and offers novel insights proposing that the pathogenesis of salt-sensitive hypertension is mediated by interaction of salt-induced hypervolemia and phosphate-induced vascular calcification. Arterial stiffness and blood pressure increase as calcification in the vascular media layer reduces arterial elasticity, preventing arteries from expanding to accommodate extracellular fluid overload in hypervolemia related to salt intake. Furthermore, phosphate has been found to be a direct inducer of vascular calcification. Reduction of dietary phosphate may help reduce salt-sensitive hypertension by lowering the prevalence and progression of vascular calcification. Further research should investigate the correlation of vascular calcification with salt-sensitive hypertension, and public health recommendations to prevent hypertension should encourage reductions of both sodium-induced hypervolemia and phosphate-induced vascular calcification.

Phosphate toxicity and SERCA2a dysfunction in sudden cardiac arrest

Almost half of the people who die from sudden cardiac arrest have no detectable heart disease. Among children and young adults, the cause of approximately one-third of deaths from sudden cardiac arrest remains unexplained after thorough examination. Sudden cardiac arrest and related sudden cardiac death are attributed to dysfunctional cardiac ion-channels. The present perspective paper proposes a pathophysiological mechanism by which phosphate toxicity from cellular accumulation of dysregulated inorganic phosphate interferes with normal calcium handling in the heart, leading to sudden cardiac arrest. During cardiac muscle relaxation following contraction, SERCA2a pumps actively transport calcium ions into the sarcoplasmic reticulum, powered by ATP hydrolysis that produces ADP and inorganic phosphate end products. Reviewed evidence supports the proposal that end-product inhibition of SERCA2a occurs as increasing levels of inorganic phosphate drive up phosphate toxicity and bring cardiac function to a sudden and unexpected halt. The paper concludes that end-product inhibition from ATP hydrolysis is the mediating factor in the association of sudden cardiac arrest with phosphate toxicity. However, current technology lacks the ability to directly measure this pathophysiological mechanism in active myocardium, and further research is needed to confirm phosphate toxicity as a risk factor in individuals with sudden cardiac arrest. Moreover, phosphate toxicity may be reduced through modification of dietary phosphate intake, with potential for employing low-phosphate dietary interventions to reduce the risk of sudden cardiac arrest.

Dysregulated phosphate metabolism in autism spectrum disorder: associations and insights for future research

Studies of autism spectrum disorder (ASD) related to exposure to toxic levels of dietary phosphate are lacking. Phosphate toxicity from dysregulated phosphate metabolism can negatively impact almost every major organ system of the body, including the central nervous system. The present paper used a grounded theory-literature review method to synthesise associations of dysregulated phosphate metabolism with the aetiology of ASD. Cell signalling in autism has been linked to an altered balance between phosphoinositide kinases, which phosphorylate proteins, and the counteracting effect of phosphatases in neuronal membranes. Glial cell overgrowth in the developing ASD brain can lead to disturbances in neuro-circuitry, neuroinflammation and immune responses which are potentially related to excessive inorganic phosphate. The rise in ASD prevalence has been suggested to originate in changes to the gut microbiome from increasing consumption of additives in processed food, including phosphate additives. Ketogenic diets and dietary patterns that eliminate casein also reduce phosphate intake, which may account for many of the suggested benefits of these diets in children with ASD. Dysregulated phosphate metabolism is causatively linked to comorbid conditions associated with ASD such as cancer, tuberous sclerosis, mitochondrial dysfunction, diabetes, epilepsy, obesity, chronic kidney disease, tauopathy, cardiovascular disease and bone mineral disorders. Associations and proposals presented in this paper offer novel insights and directions for future research linking the aetiology of ASD with dysregulated phosphate metabolism and phosphate toxicity from excessive dietary phosphorus intake.

Biases in COVID-19 Case and Death Definitions: Potential Causes and Consequences

This paper investigates three controversies involving potential causes and consequences of information bias in case and death definitions during the coronavirus disease (COVID-19) pandemic. First, evidence suggests China's surveillance data were biased and misinterpreted by the World Health Organization (WHO), prompting the WHO to advise nations to copy China's lockdowns. China appeared to use narrow diagnostic definitions that undercounted cases and deaths. Second, novel genomic data disseminated during the pandemic without adequate guidance from rigorous epidemiologic studies biased infection control policies in many countries. A novel genomic sequence of a virus is insufficient to declare new cases of a novel disease. Third, media reports of COVID-19 surveillance data in many nations appeared to be biased. Broadened surveillance definitions captured additional information, but unadjusted surveillance data disseminated to the public are not true cases and deaths. Recommendations include clarification of the proper use of diagnostic and surveillance case and death definitions to avoid information bias.

Relative risk reduction: Misinformative measure in clinical trials and COVID-19 vaccine efficacy

Treatment and vaccine efficacy in clinical trials are often reported in the media and medical journals as the relative risk reduction. The present article explains why the relative risk reduction is a misinformative measure that promotes disinformation when reporting efficacy in clinical research studies such as randomized controlled trials for COVID-19 vaccines. The relative risk reduction is based on the relative risk, a proportional measure or ratio used in epidemiologic studies to estimate the probability of a disease associated with an exposure. The present article demonstrates how the relative risk reduction and relative risk obscure the magnitude of disease risk reduction in clinical research. The absolute risk reduction is shown to be a more precise and reliable measure of treatment and vaccine efficacy in clinical research studies. The absolute risk reduction reciprocal also measures the number needed to treat or vaccinate, and is a more accurate measure than the relative risk reduction for comparing risk reductions of clinical studies. Additionally, the present article reviews consequences of COVID-19 vaccine efficacy misinformation disseminated through media reports. The article concludes that relative risk reduction should not be used to measure treatment and vaccine efficacy in clinical trials.

What is new?

•Unreliability of relative measures in clinical trials is graphically illustrated, demonstrating constant relative measures as absolute measures change.•Misuse of relative measures in clinical research is historically linked to misinterpretation of Jerome Cornfield's advice on measuring causative and associative effects.•Consequences of disinformation and misinformation related to COVID-19 vaccine efficacy and modern clinical medicine are described.•The proper use of absolute measures in meta-analyses is explained.

Hypertension, Anxiety and Obstructive Sleep Apnea in Cardiovascular Disease and COVID-19: Mediation by Dietary Salt

This perspective paper used a grounded theory method to synthesize evidence proposing that sodium toxicity from excessive dietary salt intake is a potential common pathophysiological mechanism that mediates the association of hypertension, obstructive sleep apnea, and anxiety with cardiovascular disease and COVID-19. Increased anxiety in these conditions may be linked to a high-salt diet through stimulation of the sympathetic nervous system, which increases blood pressure while releasing catecholamines, causing a "fight or flight" response. A rostral shift of fluid overload from the lower to the upper body occurs in obstructive sleep apnea associated with COVID-19 and cardiovascular disease, and may be related to sodium and fluid retention triggered by hypertonic dehydration. Chronic activation of the renin-angiotensin-aldosterone system responds to salt-induced dehydration by increasing reabsorption of sodium and fluid, potentially exacerbating fluid overload. Anxiety may also be related to angiotensin II that stimulates the sympathetic nervous system to release catecholamines. More research is needed to investigate these proposed interrelated mechanisms mediated by dietary salt. Furthermore, dietary interventions should use a whole-food plant-based diet that eliminates foods processed with salt to test the effect of very low sodium intake levels on hypertension, anxiety, and obstructive sleep apnea in cardiovascular disease and COVID-19.

Low dietary sodium potentially mediates COVID-19 prevention associated with whole-food plant-based diets

Compared with an omnivorous Western diet, plant-based diets containing mostly fruits, vegetables, grains, legumes, nuts and seeds, with restricted amounts of foods of animal origin, are associated with reduced risk and severity of COVID-19. Additionally, inflammatory immune responses and severe acute respiratory symptoms of COVID-19, including pulmonary oedema, shortness of breath, fever and nasopharyngeal infections, are associated with Na toxicity from excessive dietary Na. High dietary Na is also associated with increased risks of diseases and conditions that are co-morbid with COVID-19, including chronic kidney disease, hypertension, stroke, diabetes and obesity. This article presents evidence that low dietary Na potentially mediates the association of plant-based diets with COVID-19 prevention. Processed meats and poultry injected with sodium chloride contribute considerable amounts of dietary Na in the Western diet, and the avoidance or reduction of these and other processed foods in whole-food plant-based (WFPB) diets could help lower overall dietary Na intake. Moreover, high amounts of K in plant-based diets increase urinary Na excretion, and preagricultural diets high in plant-based foods were estimated to contain much lower ratios of dietary Na to K compared with modern diets. Further research should investigate low Na in WFPB diets for protection against COVID-19 and co-morbid conditions.

Non-Specific Low Back Pain, Dietary Salt Intake, and Posterior Lumbar Subcutaneous Edema

Low back pain is the world’s leading disability, but the etiology of the majority of low back pain is non-specific with no known cause. Moreover, overuse of opioids to treat low back pain is a widespread problem. This paper proposes that non-specific low back pain may be associated with excessive intake of dietary salt, potentially mediated by posterior lumbar subcutaneous edema. In addition to pain, symptoms of edema include swelling, tightness, and stiff joints, which are common complaints of people with low back pain, along with restricted lumbar range of motion and impaired mobility. Many global populations consume excess sodium chloride, which can lead to fluid overload in hypervolemia, and cause swelling and temporary weight gain associated with low back pain. Numerous conditions comorbid with low back pain are also potentially mediated by excessive salt intake, including migraine headache, hypertension, cardiovascular disease, venous thromboembolism, liver disease, respiratory disorders, chronic kidney disease, pregnancy complications, and multiple sclerosis. Novel approaches to identify and prevent the cause of non-specific low back pain have potential to reduce disability worldwide by reducing low back pain prevalence. More research is needed to confirm the involvement of dietary salt and posterior lumbar subcutaneous edema in non-specific low back pain.

Sodium Chloride, Migraine and Salt Withdrawal: Controversy and Insights

This paper examines evidence implicating migraine headache as a withdrawal symptom of excessive sodium chloride intake. Emerging research in food addiction posits that food and drug addictions share common features, such as withdrawal symptoms. Salt (sodium chloride) meets the criteria for the diagnosis of substance dependence, including withdrawal in which the substance is used to relieve withdrawal symptoms. The premonitory symptoms of migraine include food cravings for salty foods, which can alleviate migraine pain. Edema, possibly related to large amounts of salt consumed in binge eating, can cause approximately four pounds of retained fluid. This amount of fluid is similar to the fluid retained before the onset of migraine headache, which may be accompanied by polyuria. This paper proposes that inhibited withdrawal from highly processed food intake, rich in salt, mediates an association between increased sodium chloride intake and relief from migraine headache pain. The relief from withdrawal symptoms could also be a mediating factor that explains the controversial findings inversely associating dietary sodium intake with migraine history. Moreover, the withdrawal of retained sodium and edema related to the use of nonsteroidal anti-inflammatory drugs may elucidate a potential mechanism in medication overuse headache. Further research is needed to investigate the pain experienced from sodium chloride withdrawal in migraine headache.

Sodium Toxicity in the Nutritional Epidemiology and Nutritional Immunology of COVID-19

Dietary factors in the etiology of COVID-19 are understudied. High dietary sodium intake leading to sodium toxicity is associated with comorbid conditions of COVID-19 such as hypertension, kidney disease, stroke, pneumonia, obesity, diabetes, hepatic disease, cardiac arrhythmias, thrombosis, migraine, tinnitus, Bell's palsy, multiple sclerosis, systemic sclerosis, and polycystic ovary syndrome. This article synthesizes evidence from epidemiology, pathophysiology, immunology, and virology literature linking sodium toxicological mechanisms to COVID-19 and SARS-CoV-2 infection. Sodium toxicity is a modifiable disease determinant that impairs the mucociliary clearance of virion aggregates in nasal sinuses of the mucosal immune system, which may lead to SARS-CoV-2 infection and viral sepsis. In addition, sodium toxicity causes pulmonary edema associated with severe acute respiratory syndrome, as well as inflammatory immune responses and other symptoms of COVID-19 such as fever and nasal sinus congestion. Consequently, sodium toxicity potentially mediates the association of COVID-19 pathophysiology with SARS-CoV-2 infection. Sodium dietary intake also increases in the winter, when sodium losses through sweating are reduced, correlating with influenza-like illness outbreaks. Increased SARS-CoV-2 infections in lower socioeconomic classes and among people in government institutions are linked to the consumption of foods highly processed with sodium. Interventions to reduce COVID-19 morbidity and mortality through reduced-sodium diets should be explored further.

Outcome Reporting Bias in COVID-19 mRNA Vaccine Clinical Trials

Relative risk reduction and absolute risk reduction measures in the evaluation of clinical trial data are poorly understood by health professionals and the public. The absence of reported absolute risk reduction in COVID-19 vaccine clinical trials can lead to outcome reporting bias that affects the interpretation of vaccine efficacy. The present article uses clinical epidemiologic tools to critically appraise reports of efficacy in Pfzier/BioNTech and Moderna COVID-19 mRNA vaccine clinical trials. Based on data reported by the manufacturer for Pfzier/BioNTech vaccine BNT162b2, this critical appraisal shows: relative risk reduction, 95.1%; 95% CI, 90.0% to 97.6%; p = 0.016; absolute risk reduction, 0.7%; 95% CI, 0.59% to 0.83%; p < 0.000. For the Moderna vaccine mRNA-1273, the appraisal shows: relative risk reduction, 94.1%; 95% CI, 89.1% to 96.8%; p = 0.004; absolute risk reduction, 1.1%; 95% CI, 0.97% to 1.32%; p < 0.000. Unreported absolute risk reduction measures of 0.7% and 1.1% for the Pfzier/BioNTech and Moderna vaccines, respectively, are very much lower than the reported relative risk reduction measures. Reporting absolute risk reduction measures is essential to prevent outcome reporting bias in evaluation of COVID-19 vaccine efficacy.

Stress, inflammation, depression, and dementia associated with phosphate toxicity

Depression and dementia are predicted to increase within aging global populations. Pathophysiological effects of phosphate toxicity, dysregulated amounts of accumulated phosphorus in body tissue, are under-investigated in association with stress, inflammation, depression, and dementia. A comparative analysis of concepts in cited sources from the research literature was used to synthesize novel themes exploring the disease-oriented neuroscience effects of phosphate toxicity. Phosphate toxicity is associated with activation of cellular stress response systems and inflammation. Cortisol released by the hypothalamic-pituitary-adrenal axis responds to stress and inflammation associated with phosphate toxicity and depression. In a reciprocal interaction, phosphate toxicity is capable of harming adrenal gland function, possibly leading to adrenal insufficiency and depression. Furthermore, Alzheimer's disease is associated with hyperphosphorylated tau which self-assembles into neurofibrillary tangles from excessive amounts of phosphate in the brain and central nervous system. Future research should investigate dietary phosphate modification to reduce potential pathophysiological effects of phosphate toxicity in stress, inflammation, depression, and cognitive decline which affects global populations.

Public Health Lessons Learned From Biases in Coronavirus Mortality Overestimation

In testimony before US Congress on March 11, 2020, members of the House Oversight and Reform Committee were informed that estimated mortality for the novel coronavirus was 10-times higher than for seasonal influenza. Additional evidence, however, suggests the validity of this estimation could benefit from vetting for biases and miscalculations. The main objective of this article is to critically appraise the coronavirus mortality estimation presented to Congress. Informational texts from the World Health Organization and the Centers for Disease Control and Prevention are compared with coronavirus mortality calculations in Congressional testimony. Results of this critical appraisal reveal information bias and selection bias in coronavirus mortality overestimation, most likely caused by misclassifying an influenza infection fatality rate as a case fatality rate. Public health lessons learned for future infectious disease pandemics include: safeguarding against research biases that may underestimate or overestimate an associated risk of disease and mortality; reassessing the ethics of fear-based public health campaigns; and providing full public disclosure of adverse effects from severe mitigation measures to contain viral transmission.

Diabetes, Diabetic Complications, and Phosphate Toxicity: A Scoping Review

This article presents a scoping review and synthesis of research findings investigating the toxic cellular accumulation of dysregulated inorganic phosphate-phosphate toxicity-as a pathophysiological determinant of diabetes and diabetic complications. Phosphorus, an essential micronutrient, is closely linked to the cellular metabolism of glucose for energy production, and serum inorganic phosphate is often transported into cells along with glucose during insulin therapy. Mitochondrial dysfunction and apoptosis, endoplasmic reticulum stress, neuronal degeneration, and pancreatic cancer are associated with dysregulated levels of phosphate in diabetes. Ectopic calcification involving deposition of calcium-phosphate crystals is prevalent throughout diabetic complications, including vascular calcification, nephropathy, retinopathy, and bone disorders. A low-glycemic, low-phosphate dietary intervention is proposed for further investigations in the treatment and prevention of diabetes and related diabetic pathologies.

Potential interaction of inflammatory hyperemia and hyperphosphatemia in tumorigenesis

The present article proposes that the association of inflammation with cancer is potentially mediated by the interaction of inflammatory hyperemia and hyperphosphatemia. Hyperemia increases blood flow rate and blood volume, and hyperphosphatemia is caused by elevated serum levels of dysregulated inorganic phosphate. It is hypothesized that the interaction of inflammatory hyperemia and hyperphosphatemia circulates increased amounts of inorganic phosphate to the tumor microenvironment, where increased uptake of inorganic phosphate through sodium-phosphate cotransporters is sequestered in cells. Elevated levels of intracellular phosphorus increase biosynthesis of ribosomal RNA, leading to increased protein synthesis that supports tumor growth. The present article also proposes that the interaction of inflammatory hyperemia and hyperphosphatemia may help explain a chemopreventive mechanism associated with NSAIDs.

Vitamin D, cancer, and dysregulated phosphate metabolism

Recently reported findings from major clinical trials show no cancer protection from vitamin D supplementation, and results from observational studies of vitamin D in cancer prevention are inconsistent. There is a need for new hypotheses to guide investigations of the controversies surrounding vitamin D supplementation and cancer. Bioactive vitamin D, 1,25(OH)2D, is an endocrine factor that regulates phosphate homeostasis by increasing dietary phosphate intestinal absorption. When phosphorus serum levels are high, as in hyperphosphatemia, an endocrine feedback mechanism lowers bioactive vitamin D which reduces intestinal phosphate absorption. Low vitamin D levels have been associated with cancer incidence, and tumorigenesis is associated with high levels of dysregulated phosphate in the body. In this mini-review, the author hypothesizes that hyperphosphatemia may be an intermediating factor in the association of lowered vitamin D levels and increased risk for tumorigenesis. Furthermore, this article challenges the UVB-vitamin D-cancer hypothesis which proposes that reduced cancer incidence at lower geographic latitudes is related to high levels of vitamin D from UVB exposure. The author proposes that reduced phosphorus content and availability in tropical and subtropical soil, and lower dietary phosphate intake from consumption of tropical and subtropical crops (as in the Mediterranean diet), may mediate the association of reduced cancer risk with lower latitudes.

Phosphate toxicity and tumorigenesis

In this article, we briefly summarized evidence that cellular phosphate burden from phosphate toxicity is a pathophysiological determinant of cancer cell growth. Tumor cells express more phosphate cotransporters and store more inorganic phosphate than normal cells, and dysregulated phosphate homeostasis is associated with the genesis of various human tumors. High dietary phosphate consumption causes the growth of lung and skin tumors in experimental animal models. Additional studies show that excessive phosphate burden induces growth-promoting cell signaling, stimulates neovascularization, and is associated with chromosome instability and metastasis. Studies have also shown phosphate is a mitogenic factor that affects various tumor cell growth. Among epidemiological evidence linking phosphate and tumor formation, the Health Professionals Follow-Up Study found that high dietary phosphate levels were independently associated with lethal and high-grade prostate cancer. Further research is needed to determine how excessive dietary phosphate consumption influences initiation and promotion of tumorigenesis, and to elucidate prognostic benefits of reducing phosphate burden to decrease tumor cell growth and delay metastatic progression. The results of such studies could provide the basis for therapeutic modulation of phosphate metabolism for improved patient outcome.

Vitamin D, phosphate, and vasculotoxicity

Vascular calcification is a complex process that results in the ectopic deposition of calcium-phosphate hydroxyapatite. Medial and intimal vascular calcification is frequently present in patients with diabetes mellitus and chronic kidney disease (CKD), and markedly increases the morbidity and mortality of these patients. Increased serum levels of calcium and phosphate, along with the use of active vitamin D metabolites, are commonly implicated in the evolvement of vascular wall mineralization in CKD patients. Because CKD patients have lower serum levels of vitamin D, they are routinely prescribed vitamin D supplements that exert a dualistic role that is both healthful and harmful in these patients, perhaps protecting bone health, but at the expense of promoting vascular pathology. This review briefly explains how reducing the phosphate burden in CKD patients could minimize vitamin-D-associated vascular wall calcification.

Dysregulation of phosphate metabolism and conditions associated with phosphate toxicity

Phosphate homeostasis is coordinated and regulated by complex cross-organ talk through delicate hormonal networks. Parathyroid hormone (PTH), secreted in response to low serum calcium, has an important role in maintaining phosphate homeostasis by influencing renal synthesis of 1,25-dihydroxyvitamin D, thereby increasing intestinal phosphate absorption. Moreover, PTH can increase phosphate efflux from bone and contribute to renal phosphate homeostasis through phosphaturic effects. In addition, PTH can induce skeletal synthesis of another potent phosphaturic hormone, fibroblast growth factor 23 (FGF23), which is able to inhibit renal tubular phosphate reabsorption, thereby increasing urinary phosphate excretion. FGF23 can also fine-tune vitamin D homeostasis by suppressing renal expression of 1-alpha hydroxylase (1α(OH)ase). This review briefly discusses how FGF23, by forming a bone-kidney axis, regulates phosphate homeostasis, and how its dysregulation can lead to phosphate toxicity that induces widespread tissue injury. We also provide evidence to explain how phosphate toxicity related to dietary phosphorus overload may facilitate incidence of noncommunicable diseases including kidney disease, cardiovascular disease, cancers and skeletal disorders.

Design and evaluation of an imaging spectrophotometer incorporating a uniform light source

Accounting for light that is diffusely scattered from a surface is one of the practical challenges in reflectance measurement. Integrating spheres are commonly used for this purpose in point measurements of reflectance and transmittance. This solution is not directly applicable to a spectral imaging application for which diffuse reflectance measurements are desired. In this paper, an imaging spectrophotometer design is presented that employs a uniform light source to provide diffuse illumination. This creates the inverse measurement geometry to the directional illumination/diffuse reflectance mode typically used for point measurements. The final system had a spectral range between 400 and 1000 nm with a 5.2 nm resolution, a field of view of approximately 0.5 m by 0.5 m, and millimeter spatial resolution. Testing results indicate illumination uniformity typically exceeding 95% and reflectance precision better than 1.7%.

Buoyant plumes from solute gradients generated by non-motile Escherichia coli

The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh-Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight.

Exposure to increased pressure or hyperbaric oxygen suppresses interferon-gamma secretion in whole blood cultures of healthy humans

This study examines the effects of hyperoxia, increased atmospheric pressure, and hyperbaric oxygen on cytokine synthesis. Five healthy volunteers were exposed to 90 min of room air, 100% oxygen, 10.5% oxygen at 2 atm abs, or 100% oxygen at 2 atm abs (HBO2). All subjects were blinded and randomly exposed to each of the 4 conditions. Immediately before entering the chamber, immediately after exposure, and 3 and 24 h later, blood was drawn and stimulated ex vivo with phorbol myristate acetate (PMA) and phytohemagglutinin A (PHA). Since lymphocytes are the primary source of PMA/PHA-induced interferon-gamma (IFN-gamma), these results were expressed as IFN-gamma production per 10(6) lymphocytes. Following the HBO2 exposure, PMA/PHA-stimulated lymphocytes released 51% less IFN-gamma than cells obtained before the exposure. This suppression persisted for 24 h following HBO2 (P < 0.05). Surprisingly, increased atmospheric pressure alone also inhibited IFN-gamma secretion (P < 0.05). Room air and hyperoxia alone had no significant effect upon IFN-gamma release. HBO2's anti-inflammatory effect may, in part, be due to inhibition of IFN-gamma release.

The drug-resistant pneumococcus: clinical relevance, therapy, and prevention

Streptococcus pneumoniae has been known for > 100 years as the most important bacterial pathogen of the respiratory tract in adults and children. In recent years, the pneumococcus has begun to exhibit increasing resistance to antimicrobial agents. Because of the huge number of infections caused by this organism, the development of resistance has changed the approach to many infectious disease problems, particularly with regard to empiric antibiotic therapy and prophylaxis. In our review of the antibiotic-resistant pneumococcus, we review the microbiologic basis for resistance, risk factors for and clinical relevance of infection by a resistant organism, and infection control measures.

Managing by numbers: using outcome measures in the NHS

The paper explores the literature concerning outcome measures used in health services. The need to measure outcomes subsequent to encounters with health services has been identified and occurs as a result of the current "value for money" approaches being used within the NHS. Provider units are required to establish the effects which interventions have had on the health of each individual using their services, despite the fact that definitions of health outcomes used by both professionals and managers are problematic. It is suggested here, however, that outcome measures which answer all requirements will remain elusive, and their effectiveness will vary according to the circumstances of their generation and use. Moreover, the very use of outcome measures as management tools can lead to a subversion of the meaning which led to their selection in the first place. Managing by (outcome measure) numbers is not a realistic way forward.

A method to track surgical site infections

We present an approach to assessing the impact of surveillance for surgical site infections and providing feedback to surgeons on their progress, as part of continuous quality improvement. Adjusting for patient risk factors using the Standardized Mortality Ratio, there was a marked decrease over time in both SMR (1.3 to 0.27) and crude infection rates (32 to 10 per thousand operations per year). These declines cannot be explained by decreased length of hospital stay.

Outpatient parenteral antibiotic therapy in the management of community-acquired lower respiratory infections

Within the past several years, the decision to employ outpatient parenteral antibiotic therapy (OPAT) is driven by adequacy of insurance, availability of appropriate resources within the community, and the clinical stability of the patient. Current dogma is that virtually any diagnosed disease can be treated outside the hospital, provided the former criteria are met. The decision to utilize OPAT is complex and involves a number of decision points that relate to the patient, the disease and pathogen, the antibiotic, and the facilities available in the community. This article discusses the decision-making process to utilize OPAT or hospitalization for community-acquired lower respiratory infections.

Aetiologies and outcomes of wounds in an outpatient programme

This study reviewed the records of all new patients seen in an outpatient wound-care programme during a six-month period. Most of the 115 patients were referred by physicians in internal medicine or family practice (48%) or surgeons (39%); 101 had a wound (88%). Of the 92 who had their wound measured at the time of their first clinic visit, 72 (78%) had their largest wound located on a lower extremity and 40% of all lower extremity wounds were on the feet. Wounds were most frequently due to pressure (36%), venous insufficiency (16%), diabetic neuropathy (16%), or arterial insufficiency (13%). Within 12 months of their initial presentation, wound closure was documented in 35 of the 92 patients (38%). Of the four most common aetiologies, the healing rate was highest in wounds attributable to venous insufficiency (67%) (p < 0.02).

Hereditary ataxia with sensory neuronopathy: Biemond's ataxia

We report the case of a man with late-onset hereditary ataxia and sensory loss. Three of his sisters were affected by a similar disorder; to date no other members of his family have developed symptoms. The clinical features of this family are similar to a rare form of autosomal dominant hereditary ataxia, recently classified as SCA4. Postmortem findings indicate that this syndrome is marked by degeneration of cerebellar Purkinje cells, dorsal root sensory ganglion neurons, and the ascending posterior columns. Similar clinical and pathologic findings were reported by Biemond in 1954.

Organizational Commitment: Clarifying the Concept and Simplifying the Existing Construct Typology

This paper examines popular concepts and "types" of organizational commitment in light of the definition of commitment and common factors that pertain to all commitments. It argues that a commitment is best conceptualized as a single, fundamental construct that may vary according to differences in focus, terms, and time-specific evaluation. Analysis of affective commitment measures indicates that certain measures contain more than one set of terms and make assumptions about evaluation that add constraints to the basic meaning of commitment. Recommendations include the argument that commitment measures address one set of terms and avoid evaluative phraseology.

Why the NHS should abandon the search for the universal outcome measure

This paper considers the use of outcome measures in the British National Health Service (NHS). Measuring outcomes is a major conceptual and practical problem. Many different measures are currently available yet no consensus has been reached on which should be preferred over others, or about which should take priority when they conflict. Some currently used measures are described, the relationship between these measures and the measured activities are discussed, and fundamental problems with both the measures and their use are revealed. It is shown that however assiduous the search, the 'perfect' outcome measure will always remain elusive.

Involving patients in the provision of community care: a change in philosophy

The National Health Service (NHS) has many different kinds of professionals and managers working underneath its large umbrella: non-clinical managers administer the work of health-care professionals, who in turn are concerned with the management of patients' treatments. Delivery of health-care services involves the managers and professionals working together to achieve a service that is good for, and acceptable to, patients. A change in the philosophy of the NHS is indicated by the growing acceptance, by both managers and professionals, of the necessity to elicit the views of patients (i.e. the expectations and perceptions of service users) and to incorporate these views into the planning and implementation of services. Discusses one such attempt to elicit the perceptions of service users, and reports on the preliminary findings of a patient-centred audit which has been undertaken in Southend Community Care Services NHS Trust. Discusses the effects that the audit has had on the chiropody services in Southend, for both non-clinical managers and health-care professionals, in order to highlight the usefulness of the approach.

Outpatient treatment of community-acquired pneumonia in adults

Most adults with community-acquired pneumonia are treated as outpatients. Despite this, the majority of studies regarding community-acquired pneumonia have been in hospitalized patients only and may not be applicable to an ambulatory population. This review critically examines the literature regarding the diagnosis, cause, appropriate patient selection, and treatment of nonhospitalized adults with community-acquired pneumonia, including human immunodeficiency virus-infected individuals. English-language articles on oral antibiotic trials for community-acquired pneumonia, obtained from a MEDLINE search from 1966 to the present, are reviewed. Etiologic diagnosis is helpful in determining appropriate outpatient treatment for community-acquired pneumonia, and usually requires only sputum Gram's stain analysis. Viral, mycoplasmal, and chlamydial agents are among the most common pathogens encountered in individuals treated as outpatients, although much variability exists. Many oral antibiotic trials for community-acquired pneumonia have been published, but shortcomings in study design limit their clinical applicability. A treatment algorithm is offered, using the best available data.

Community-acquired bacteremias from tunneled central intravenous lines: results from studies of a single vendor

Tunneled central intravenous catheters are a common method for rendering prolonged outpatient intravenous therapy. Their safety, however, has not been well studied. We conducted a retrospective evaluation of bacteremias associated with tunneled central intravenous catheters managed by a single home health care vendor during a 1-year period. All catheters were inserted in the operating room under sterile conditions. To calculate total line days, the dates of catheter insertion and removal were obtained from either the hospital operating room or the home health care agency. Catheter care was conducted according to written protocols. Total line days were calculated. Community-acquired bacteremia (defined as bacteremia occurring more than 6 days after the patients' discharge from the hospital) was determined from records available in the infection control department. Sixty-eight patients received intravenous therapy from the vendor during the 1-year study period. Total line days were 5548 (median 52 days/patient). Eleven episodes of bacteremia occurred in five patients, providing an incidence density rate of 2.0 infections/1000 catheter days. The most frequent bacteria encountered were Staphylococcus epidermidis (five), Klebsiella pneumoniae (two), and Acinetobacter calcoaceticus var anitratus (two). Median time to bacteremia was 103 days. Two patients, both younger than 4 years, accounted for seven of the infections; both had short-bowel syndrome. On the basis of historical comparisons, outpatient intravenous therapy appears to be associated with a lower risk of bacteremia than in-hospital therapy. These data can provide quality improvement information and may be a means for comparing home infusion therapy vendors.

Laparoscopic hernia repair: a rural perspective

Laparoscopic hernia repair has been used successfully to repair inguinal as well as some ventral, incisional, and umbilical hernias. The laparoscopic approach is favored by patients because they experience little, if any, postoperative pain and enjoy a rapid return to unrestricted activity. We repaired 84 hernias in 61 patients from March 1991 to December 1992. All patients were treated by the author in rural west-central Minnesota hospitals, each of which has 30 beds or less. A unique preperitoneal patch design was used, and a novel technique for the dissection of an indirect hernia sac was developed. The patient population treated was older than that reported in other series, with an average age of 55 and a median age of 61 years. Based on postoperative interviews, 95% of the patients reported being satisfied with the procedure and their outcome. All ten patients who had also experienced traditional hernia surgery preferred the laparoscopic repair. They cited less postoperative pain and a quicker return to full activity as the main reasons for their preference. Of the three patients who had a recurrence of their hernia, two have had a repeat laparoscopic hernioplasty without subsequent recurrence. The third patient has indicated that he plans to have his recurrent hernia repaired laparoscopically again. One hundred percent of the patients indicated that they would choose to have a laparoscopic hernia repair should they need another hernia repaired in the future.

Who is the NHS for?

The immediate, common sense answer to the question, "Who is the NHS for?" would obviously be, "The patients who use it". This may well be the fundamental purpose of the NHS, yet it would appear that differing views of how this is to be achieved contribute to a misreading between stakeholders of each others' remit. The different positions taken by the two most important NHS stakeholders, the professional clinicians and the administrative managers, affect their definitions of, and therefore their attitudes to their own contribution to the purpose of the NHS. Suggests that before priorities in health care can be considered and discussed, let along be set, consensual agreement needs to be reached concerning the views of professional clinicians and managers of ways of achieving their vision of who the NHS is for.

Carcass and meat sensory traits of steers finished on fescue and clover, summer forage, or for different periods in drylot

During a 3-yr period 184 steers were allotted to five treatment groups. Group 1 steers were pastured on fescue-clover and slaughtered in the spring at approximately 540 d of age. Group 2 steers were pastured on fescue-clover then placed on summer pasture regimens and slaughtered at approximately 620 d of age. Group 3 steers were treated the same as Group 2 then placed in the drylot for 45 d. Group 4 steers were treated the same as Group 2 steers then placed in the drylot for 75 d. Group 5 steers were placed in drylot after weaning and conditioning and were slaughtered at endpoints that corresponded with those for Group 3. Steers selected for slaughter at each endpoint were those evaluated to have reached the most optimum slaughter weight and finish by project personnel. Carcasses of steers from fescue-clover and summer pasture had lower yield grades and a lower quality grade than carcasses of steers from drylot (P < .05). Carcasses of steers from fescue-clover and summer pasture had a more yellow fat covering than carcasses of steers that received a concentrate (Treatments 3, 4, and 5, P < .0001). Fescue-clover- and summer pasture-fed steers had a higher percentage of lean and a lower percentage of fat in the 9-10-11th rib section than did steers that received concentrate (P < .005). Chemical analysis of the lean tissue of the 9-10-11th rib section indicated that summer pasture-fed steers had a lower percentage of ether extract and higher percentage of moisture than the lean tissue from steers that received concentrate (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperpyrexia among patients in a large community hospital: causes, features, and outcomes

Hyperpyrexia, defined as temperature elevation of at least 106 degrees F, is generally thought to be infrequently associated with infection. In a 3-year retrospective analysis of 39 episodes of hyperpyrexia in adults, 94% of cases were associated with infection. In 35 patients (90%) the causes were potentially treatable, and the majority were associated with common bacteria or fungi. Fourteen (36%) patients were bacteremic. Fifteen (43%) of those with treatable infections had additional noninfectious reasons for hyperpyrexia. Only three patients died in conjunction with hyperpyrexia, and none of these had treatable infection. Infection must be strongly considered by the clinician faced with a hyperpyrexic patient. Antimicrobial therapy is indicated in the majority of cases, and most patients will survive through hospital discharge.