Quantifying the frequency and volume of urine deposition by grazing sheep using tri-axial accelerometers.

Urine patches deposited in pasture by grazing animals are sites of reactive nitrogen (N) loss to the environment due to high concentrations of N exceeding pasture uptake requirements. In order to upscale N losses from the urine patch, several urination parameters are required, including where, when and how often urination events occur as well as the volume and chemical composition. There are limited data available in this respect, especially for sheep. Here, we seek to address this knowledge gap by using non-invasive sensor-based technology (accelerometers) on ewes grazing in situ, using a Boolean algorithm to detect urination events in the accelerometer signal. We conducted an initial study with penned Welsh Mountain ewes (n = 5), with accelerometers attached to the hind, to derive urine flow rate and to determine whether urine volume could be estimated from ewe squat time. Then accelerometers attached to the hind of Welsh Mountain ewes (n = 30 at each site) were used to investigate the frequency of sheep urination events (n = 35 946) whilst grazing two extensively managed upland pastures (semi-improved and unimproved) across two seasons (spring and autumn) at each site (35-40 days each). Sheep urinated at a frequency of 10.2 ± 0.2 and 8.1 ± 0.3 times per day in the spring and autumn, respectively, while grazing the semi-improved pasture. Urination frequency was greater (19.0 ± 0.4 and 15.3 ± 0.3 times per day in the spring and autumn, respectively) in the unimproved pasture. Ewe squat duration could be reliably used to predict the volume of urine deposited per event and was thus used to estimate mean daily urine production volumes. Sheep urinated at a rate of 16.6 mL/s and, across the entire dataset, sheep squatted for an average of 9.62 ± 0.03 s per squatting event, producing an estimated average individual urine event volume of 159 ± 1 mL (n = 35 946 events), ranging between 17 and 745 mL (for squat durations of 1 to 45 s). The estimated mean daily urine volume was 2.15 ± 0.04 L (n = 2 669 days) across the entire dataset. The data will be useful for modelling studies estimating N losses (e.g. ammonia (NH3) volatilisation, nitrous oxide (N2O) emission via nitrification and denitrification and nitrate (NO3-) leaching) from urine patches.

Overriding water table control on managed peatland greenhouse gas emissions.

Global peatlands store more carbon than is naturally present in the atmosphere1,2. However, many peatlands are under pressure from drainage-based agriculture, plantation development and fire, with the equivalent of around 3 per cent of all anthropogenic greenhouse gases emitted from drained peatland3-5. Efforts to curb such emissions are intensifying through the conservation of undrained peatlands and re-wetting of drained systems6. Here we report eddy covariance data for carbon dioxide from 16 locations and static chamber measurements for methane from 41 locations in the UK and Ireland. We combine these with published data from sites across all major peatland biomes. We find that the mean annual effective water table depth (WTDe; that is, the average depth of the aerated peat layer) overrides all other ecosystem- and management-related controls on greenhouse gas fluxes. We estimate that every 10 centimetres of reduction in WTDe could reduce the net warming impact of CO2 and CH4 emissions (100-year global warming potentials) by the equivalent of at least 3 tonnes of CO2 per hectare per year, until WTDe is less than 30 centimetres. Raising water levels further would continue to have a net cooling effect until WTDe is within 10 centimetres of the surface. Our results suggest that greenhouse gas emissions from peatlands drained for agriculture could be greatly reduced without necessarily halting their productive use. Halving WTDe in all drained agricultural peatlands, for example, could reduce emissions by the equivalent of over 1 per cent of global anthropogenic emissions.

The association of HIV and cocaine use to cigarette smoking in the context of depression and perceived stress.

Mental well-being can contribute to cigarette smoking and negatively impact disease progression among people living with HIV (PLWH). This study examined potential associations between cocaine use (COC), depression, and HIV status in predicting cigarette smoking; hypothesizing that depression would be highest in cocaine users and predict cigarette smoking. An exploratory analysis including stress was also examined as a potential predictor of cigarette use. More than half of the sample (65%) endorsed smoking at some point in the past, and 52% endorsed being current smokers at the time of the study. Smokers were most likely to be cocaine users (87.1%), cocaine using PLWH (74.3%), or PLWH (36.6%). Neither HIV status (χ2(1) = 1.5, p = .221), perceived stress (χ2(1) = 0.75 p = .386), nor depressive symptomatology (χ2(1) = 1.2, p = .274) were related to smoking. Non-cocaine users were approximately 95.4% less likely to smoke than cocaine users, controlling for all other variables. Overall, cocaine use was the greatest predictor of cigarette smoking and quantity of cigarettes smoked. Perceived stress and depression were not associated with cigarette smoking in the sample. Future interventions targeting cigarette use should include a cocaine-related component to encourage smoking cessation among this high-risk group.

Subclinical infection and asymptomatic carriage of gastrointestinal zoonoses: occupational exposure, environmental pathways, and the anonymous spread of disease.

Asymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks. Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

Survival analysis of an asymmetric primary total knee replacement: a European multicenter prospective study.

PURPOSE OF THE STUDY: This multicenter prospective study objective is to provide midterm results and 10-year survival analysis of the original Natural Knee-I System™ as experienced by a group of surgeons performing, within various settings, primary total knee replacement (TKR) in the general population. HYPOTHESIS: The midterm experience with this TKR system in the hands of independent surgical teams can duplicate the satisfaction level that was already published by the designer's group itself. MATERIAL AND METHOD: Two hundred and sixty-three primary TKR were performed by seven surgical teams (37 surgeons) and prospectively evaluated in four European countries. Mean age of the 263 patients (sex ratio, 2.7 females/1 male) was 69 years (range, 35-92) and diagnosis was primary osteoarthritis in 85%. For the 247 TKR with complete operative data, the approach was subvastus in 59%, posterior cruciate ligament was spared in 78%, patella was resurfaced in 56%, and 79% of reconstructions were totally cement-free. Fixation mode was only depending on the surgeon's choice. RESULTS: At 76 months average follow-up (range 24-190 months), modified Hospital for Special Surgery knee mean score improved from 48 points preoperatively to 83 points. Four reoperations and five revision procedures were required for eight knees. Over the 14-year survey period, the overall revision rate burden was 2% and revision rate per 100 observed component/year, 0.32. At 10 years, survivorship (with revision for aseptic loosening as its end-point [two fully cementless knees]) was 98.6%. DISCUSSION: Both this multicenter study and data drawn from national registers provided outcomes with equivalent level of satisfaction at equivalent follow-up to those reported by the NK-I prosthesis designer. There was no significant difference between revision rates of cemented, hybrid or cementless reconstructions. CONCLUSION: In non-designer orthopaedists' hands, the Natural Knee-I System™, either with cemented or cementless fixation, provided satisfying midterm results as normally expected in primary TKR with such a modern modular prosthesis. LEVEL OF EVIDENCE: Level IV. Prospective study.

Coordinate downregulation of CaM kinase II and phospholamban accompanies contractile phenotype transition in the hyperthyroid rabbit soleus.

This study investigated the effects of l-thyroxine-induced hyperthyroidism on Ca(2+)/calmodulin (CaM)-dependent protein kinase (CaM kinase II)-mediated sarcoplasmic reticulum (SR) protein phosphorylation, SR Ca(2+) pump (Ca(2+)-ATPase) activity, and contraction duration in slow-twitch soleus muscle of the rabbit. Phosphorylation of Ca(2+)-ATPase and phospholamban (PLN) by endogenous CaM kinase II was found to be significantly lower (30-50%) in soleus of the hyperthyroid compared with euthyroid rabbit. Western blotting analysis revealed higher levels of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) 1 ( approximately 150%) Ca(2+) pump isoform, unaltered levels of SERCA2 Ca(2+) pump isoform, and lower levels of PLN ( approximately 50%) and delta-, beta-, and gamma-CaM kinase II (40 approximately 70%) in soleus of the hyperthyroid rabbit. SR vesicles from hyperthyroid rabbit soleus displayed approximately twofold higher ATP-energized Ca(2+) uptake and Ca(2+)-stimulated ATPase activities compared with that from euthyroid control. The V(max) of Ca(2+) uptake (in nmol Ca(2+).mg SR protein(-1).min(-1): euthyroid, 818 +/- 73; hyperthyroid, 1,649 +/- 90) but not the apparent affinity of the Ca(2+)-ATPase for Ca(2+) (euthyroid, 0.97 +/- 0.02 microM, hyperthyroid, 1.09 +/- 0.04 microM) differed significantly between the two groups. CaM kinase II-mediated stimulation of Ca(2+) uptake by soleus muscle SR was approximately 60% lower in the hyperthyroid compared with euthyroid. Isometric twitch force of soleus measured in situ was significantly greater ( approximately 36%), and the time to peak force and relaxation time were significantly lower ( approximately 30-40%), in the hyperthyroid. These results demonstrate that thyroid hormone-induced transition in contractile properties of the rabbit soleus is associated with coordinate downregulation of the expression and function of PLN and CaM kinase II and selective upregulation of the expression and function of SERCA1, but not SERCA2, isoform of the SR Ca(2+) pump.

Transcriptome profiling of a Saccharomyces cerevisiae mutant with a constitutively activated Ras/cAMP pathway.

Often changes in gene expression levels have been considered significant only when above/below some arbitrarily chosen threshold. We investigated the effect of applying a purely statistical approach to microarray analysis and demonstrated that small changes in gene expression have biological significance. Whole genome microarray analysis of a pde2Delta mutant, constructed in the Saccharomyces cerevisiae reference strain FY23, revealed altered expression of approximately 11% of protein encoding genes. The mutant, characterized by constitutive activation of the Ras/cAMP pathway, has increased sensitivity to stress, reduced ability to assimilate nonfermentable carbon sources, and some cell wall integrity defects. Applying the Munich Information Centre for Protein Sequences (MIPS) functional categories revealed increased expression of genes related to ribosome biogenesis and downregulation of genes in the cell rescue, defense, cell death and aging category, suggesting a decreased response to stress conditions. A reduced level of gene expression in the unfolded protein response pathway (UPR) was observed. Cell wall genes whose expression was affected by this mutation were also identified. Several of the cAMP-responsive orphan genes, upon further investigation, revealed cell wall functions; others had previously unidentified phenotypes assigned to them. This investigation provides a statistical global transcriptome analysis of the cellular response to constitutive activation of the Ras/cAMP pathway.

The effect of growth hormone (GH) replacement therapy in adult patients with type 1 diabetes mellitus and GH deficiency.

OBJECTIVES: Specific problems in patients with insulin-dependent diabetes mellitus (IDDM) and GH deficiency are hypoglycaemic attacks, increased insulin sensitivity and loss of energy. These problems may be related to GH deficiency. PATIENTS: GH replacement was initiated in five patients with type 1 diabetes mellitus and GH deficiency for 6 months [four males and one female, mean age 41.6 +/- 3.8 years, mean +/- standard error of the mean (SEM); body mass index (BMI) 22.3 +/- 1.2 kg/m2]. METHODS: Body composition (bioimpedance), metabolic control [haemoglobin A1C (HbA1C)], insulin requirement and frequency of hypoglycaemia were measured, and quality of life was assessed using validated questionnaires. Monthly eye photographs were taken. RESULTS: IGF-I concentrations were below the age-adjusted range at baseline and increased significantly following GH replacement therapy [analysis of variance (ANOVA), P < 0.05]. Diabetes control as assessed by HbA1C remained stable (8.2 +/- 0.2 vs. 8.0 +/- 0.4), but needed a 1.75-fold increase in insulin dose/day. Lean body mass tended to increase (P = 0.07) and body fat mass decreased significantly (P > 0.01). Number of severe hypoglycaemic (< 3 mmol/l) attacks decreased significantly (P < 0.04) and quality of life assessed by validated questionnaires improved significantly in all patients [Psychological and General Well-Being Schedule (PGWBS), P < 0.04; Nottingham Health Profile (NHP), P < 0.05]. Monthly eye photographs revealed no changes in the retina in any patients. CONCLUSION: GH replacement therapy has a beneficial effect at the dose used. It restores body composition and decreases frequency and severity of hypoglycaemic episodes, thus improving quality of life. Long-term trials are needed to determine the safety of GH replacement therapy in these patients.

Does GH replacement therapy in adult GH-deficient patients result in recurrence or increase in size of pituitary tumours?

OBJECTIVE: Hypopituitary GH-deficient patients have an increased cardiovascular mortality and GH replacement in this population has resulted in considerable therapeutic benefit. GH replacement involves administration of a potentially mitogenic substance to patients with a previous or residual pituitary tumour. Our objective was to evaluate whether GH replacement results in an increase in the size of pituitary tumours. METHODS: This was a non-randomised observational study on patients recruited from the endocrine clinic. All subjects had GH deficiency, proven on an insulin tolerance test and were divided into those who were or were not receiving long-term GH replacement. Comparison of change in pituitary size was made with interval radiological imaging of the pituitary. RESULTS: Seventy-five patients (40 men and 35 women) were in the study, 47 were on long-term GH replacement and there were 28 controls. The average length of treatment for the treated group was 3.6 patient years. Thirty-nine patients in the treated group had at least 2 years of GH treatment between imaging studies of the pituitary. Two patients in the treated group had an increase in pituitary size (non-functioning adenomas) and two in the control group (one functioning and one non-functioning adenoma adenoma). None of these four patients required further treatment. There was no statistically significant difference between the two groups. CONCLUSION: Using a representative cohort of hypopituitary patients attending an endocrine clinic, GH replacement was not associated with an increased pituitary tumour recurrence rate. Although the results are not conclusive, in the period of observation GH had little adverse effect but longer studies are required to be certain.

The HPV E7 oncoprotein inhibits tumor necrosis factor alpha-mediated apoptosis in normal human fibroblasts.

Tumor necrosis factor-alpha (TNF) is a cytokine that induces programmed cell death, apoptosis, in a number of cell types and is employed by cytotoxic T cells to eliminate virus infected cells. Consequently, many viruses have acquired mechanisms to undermine these host cell defense mechanisms and cause resistance to TNF-mediated apoptosis. Here we show that normal human diploid fibroblasts that express the human papillomavirus type 16 E7 oncoprotein have a decreased propensity to undergo apoptosis in response to TNF treatment. The ability of E7 to undermine TNF-mediated apoptosis correlates with cellular transformation. While E7 does not generally subvert signaling by tumor necrosis factor receptor 1, pro-caspase 8 activation is decreased in E7-expressing cells. E7 also provides some protection from apoptosis caused by stimulation of the TNF receptor 1-related cytokine receptor Fas, where induction of apoptosis occurs much slower in this cell type. Hence, E7-expressing normal human fibroblasts exhibit a specific defect that obstructs cytokine-mediated activation of pro-caspase 8 and apoptosis.

The use of modularity in revision total hip replacement.

A study was undertaken to establish the pattern of components revised in recent years during total hip revision to establish how often a modular feature of a retained component was used. All total hip revisions performed by the total joint service of the University Hospital between 1991 and 1995 were reviewed. Revisions involving a surface replacement, endoprosthesis, bipolar stem, or infection were excluded because retention of components is not an option in these cases. This left 158 cases for review. If a modular femoral or acetabular component was retained, it was determined whether a different length of modular head or different liner type was replanted, thus using a modular feature of the component. The most common pattern of component revision was to revise all components, which was done in 77 of 158 cases (48.7%). The second most common pattern was to revise a socket and leave the stem in place (53/158, 33.5%). The third most common was to revise the stem and leave the socket in place (22/158, 13.9%). The least common was to retain both the stem and socket and exchange the head and liner (6/158, 3.8%). Of the 59 cases in which the stem was retained, a modular head of a different length was used in 52 (88%). Of the 28 cases in which a socket was retained, a different liner type was used in 14 (50%). The modular aspect of the retained component was a valuable asset at the time of revision in a high percentage of cases (66/158, 41.8%).

Lack of correlation between psychological factors and subclinical coronary artery disease.

BACKGROUND: The relation between psychological variables and clinically evident coronary artery disease has been studied extensively, although the potential mechanisms of such a relation remain speculative. We studied the relation between multiple psychological variables and subclinical coronary artery disease to assess the possible role of such variables in atherogenesis. METHODS: We conducted a prospective study of 630 consecutive consenting, active-duty U.S. Army personnel, 39 to 45 years of age, without known coronary artery disease. Each participant was assessed for depression, anxiety, somatization, hostility, and stress. Subclinical coronary artery disease was identified by electron-beam computed tomography. RESULTS: The mean (+/-SD) age of the subjects was 42+/-2 years; 82 percent were male, and 72 percent were white. The prevalence of coronary-artery calcification was 17.6 percent (mean calcification score, 10+/-49). The prevalence of prior or current psychiatric disorders was 12.7 percent. There was no correlation between the coronary-calcification score and the scores measuring depression (r= -0.07, P=0.08), anxiety (r=-0.07, P=0.10), hostility (r=-0.07, P=0.10), or stress (r=-0.002, P=0.96). Somatization (the number and severity of durable physical symptoms) was inversely correlated with calcification scores (r=-0.12, P=0.003), even after we controlled for age and sex. In multivariate logistic-regression models, a somatization score greater than 4 (out of a possible 26) was independently associated with the absence of any coronary-artery calcification (odds ratio, 0.49; 95 percent confidence interval, 0.25 to 0.96). CONCLUSIONS: Our data suggest that depression, anxiety, hostility, and stress are not related to coronary-artery calcification and that somatization is associated with the absence of calcification.

Treatment of nicotine addiction.

The best available data show smoking to be by far the most important cause of disease and death in our society, contributing to an average of 1000 deaths every day. Although a large majority of current smokers express a desire to quit, the majority of "self-help" attempts to quit are not successful. Further, most smokers indicate never having received advice on cessation from healthcare providers. The combination of pharmacotherapy and behavioral interventions, even on a minimal level, have been shown to be effective in cessation. Such strategies are certainly highly cost-effective, given the enormous costs to society of smoking-related illnesses. Therefore, it is important that all healthcare providers provide at least some form of smoking cessation programs for their patients.

Serine phosphorylation of the sarcoplasmic reticulum Ca(2+)-ATPase in the intact beating rabbit heart.

Recent studies have demonstrated that Ca(2+)/calmodulin-dependent protein kinase phosphorylates the Ca(2+)-pumping ATPase of cardiac sarcoplasmic reticulum (SR) in vitro. Also, evidence from in vitro studies suggested that this phosphorylation, occurring at Ser(38), results in stimulation of Ca(2+) transport. In the present study, we investigated whether serine phosphorylation of the SR Ca(2+)-ATPase occurs in the intact functioning heart. Hearts removed from anesthetized rabbits were subjected to retrograde aortic perfusion of the coronary arteries with oxygenated mammalian Ringer solution containing (32)P(i) and contractions were monitored by recording systolic left ventricular pressure development. Following 45-50 min of (32)P perfusion, the hearts were freeze-clamped, SR isolated, and analyzed for protein phosphorylation. SDS-polyacrylamide gel electrophoresis and autoradiography showed phosphorylation of several peptides including the Ca(2+)-ATPase and Ca(2+) release channel (ryanodine receptor). The identity of Ca(2+)-ATPase as a phosphorylated substrate was confirmed by Western immunoblotting as well as immunoprecipitation using a cardiac SR Ca(2+)-ATPase-specific monoclonal antibody. The Ca(2+)-ATPase showed immunoreactivity with a phosphoserine monoclonal antibody indicating that the in situ phosphorylation occurred at the serine residue. Quantification of Ca(2+)-ATPase phosphorylation in situ yielded a value of 208 +/- 12 pmol (32)P/mg SR protein which corresponded to the phosphorylation of approximately 20% of the Ca(2+) pump units in the SR membrane. Since this phosphorylation occurred under basal conditions (i.e., in the absence of any inotropic intervention), a considerable steady-state pool of serine-phosphorylated Ca(2+)-ATPase likely exists in the normally beating heart. These findings demonstrate that serine phosphorylation of the Ca(2+)-ATPase is a physiological event which may be important in the regulation of SR function.

Growth hormone replacement therapy in adults with growth hormone deficiency improves vascular reactivity.

OBJECTIVE: Patients with adult growth hormone (GH) deficiency are thought to be of increased risk of cardiovascular disease. Impaired vascular reactivity to endothelium derived nitric oxid (NO) is an early event in the development of atherosclerosis. In order to detect a possible effect of GH on vascular endothelium we examined forearm vasodilator responses in 8 patients with adult GH-deficiency before and after 3 months GH replacement therapy. METHODS: Forearm blood flow studies were performed using venous occlusion plethysmography. Blood flow was measured at baseline and during intra-arterial infusions of 3 cumulative doses (7.5, 15 and 30 microg/minutes) of acetylcholine chloride and of sodium nitroprusside (1, 3 and 10 microg/minutes). Fasting blood samples were collected for measurement of lipid profile, Haemoglobin A1C (HbA1C), glucose, IGF-I and insulin. RESULTS: GH replacement therapy significantly increased IGF-I concentrations and tended to increase fasting insulin concentrations (IGF-I: 72.7 +/- 12.4 vs. 130.8 +/- 18.5 microg/l, P < 0.001; fasting insulin: 14.3 +/- 3.4 vs. 32.9 +/- 18.6, mU/l, P = 0.06). Fasting lipid profile, glucose and HbA1C did not significantly change. Blood flow responses to acetylcholine were significantly greater after GH replacement therapy (10.3 +/- 1.0 vs. 17.6 +/- 2.5 ml/minutes/100 ml for the highest dose, P < 0.03). There was a strong tendency to increased blood flow response to nitroprusside after GH therapy (10.7 +/- 1.2 vs. 17.5 +/- 1.7 ml/minutes/100 ml for the highest dose, P = 0.06). CONCLUSION: These findings suggest that GH replacement therapy may have a beneficial effect on endothelium function which is independent of quantitative changes in fasting lipid profile.

Expression of the HPV E7 oncoprotein mimics but does not evoke a p53-dependent cellular DNA damage response pathway.

Acute expression of the human papillomavirus E7 oncoprotein in preimmortal human fibroblasts induces changes in the abundances of multiple cellular regulatory proteins. These alterations include a destabilization of the retinoblastoma tumor suppressor protein pRB, stabilization of the tumor suppressor protein p53, and increases in the level of the cyclin-dependent kinase inhibitor p21(cip1). Since the HPV E7 oncoproteins can interfere with several cell cycle checkpoints and similar alterations in the levels of pRB, p53, and p21(cip1) are also observed in a p53-dependent response to DNA damage, we investigated whether E7 expression triggers this signal transduction pathway. The results demonstrate that E7-mediated destabilization of pRB does not require p53 activity and is independent of the ability of E7 to induce apoptosis. Moreover, E7-mediated increases in p21(cip1) levels are largely p53-independent and involve stabilization of the p21(cip1) protein. In contrast the decreases in pRB expression in response to DNA damage involve transcriptional downregulation of RB gene expression.

Rationale and design of the Prospective Army Coronary Calcium (PACC) Study: utility of electron beam computed tomography as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty United States Army Personnel.

BACKGROUND: Screening for coronary artery calcium with electron beam computed tomography (EBCT) has potential diagnostic and prognostic implications. Most prior research on this technology has been done on selected, high-risk populations. The goal of the Prospective Army Coronary Calcium (PACC) study is to determine the utility of EBCT for the detection of coronary calcium as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty personnel undergoing the United States Army's Cardiovascular Screening Program. METHODS AND RESULTS: Three study designs will be used to address the objectives of this investigation: (1) a cross-sectional study of 2000 unselected, consecutive participants to determine the prevalence and extent of coronary calcification in the 40- to 45-year-old Army population, (2) a randomized, controlled trial with a 2 x 2 factorial design involving 1000 participants to assess the impact of EBCT information on several dimensions of patient behavior, with and without intensive risk factor case management, and (3) a prospective cohort study of 2000 participants followed for at least 5 years to establish the relation between coronary calcification and cardiovascular events in an unselected, "low-risk" (by conventional standards) Army population. CONCLUSIONS: We present a review of the literature on the clinical utility of EBCT, with a focus on the limited research in young, asymptomatic populations. The details of the PACC study (begun in October1998) are presented. The results of the PACC study will determine the clinical utility of EBCT in young, asymptomatic patients.

Effect of aluminum on cytoplasmic Ca2+ homeostasis in root hairs of Arabidopsis thaliana (L.).

Aluminum inhibition of root growth is a major world agricultural problem where the cause of toxicity has been linked to changes in cellular calcium homeostasis. Therefore, the effect of aluminum ions (Al) on changes in cytoplasmic free calcium concentration ([Ca2+]c) was followed in root hairs of wild-type, Al-sensitive and Al-resistant mutants of Arabidopsis thaliana (L.) Heynh. Generally, Al exposure resulted in prolonged elevations in tip-localized [Ca2+]c in both wild-type and Al-sensitive root hairs. However, these Al-induced increases in [Ca2+]c were not tightly correlated with growth inhibition, occurring up to 15 min after Al had induced growth to stop. Also, in 32% of root hairs examined growth stopped without a detectable change in [Ca2+]c. In contrast, Al-resistant mutants showed little growth inhibition in response to AlCl3 exposure and in no case was a change in [Ca2+]c observed. Of the other externally applied stresses tested (oxidative and mechanical stress), both were found to inhibit root hair growth, but only oxidative stress (H2O2, 10 microM) caused a prolonged rise in [Ca2+]c similar to that induced by Al. Again this increase occurred after growth had been inhibited. The lack of a tight correlation between Al exposure, growth inhibition and altered [Ca2+]c dynamics suggests that although exposure of root hairs to toxic levels of Al causes an alteration in cellular Ca2+ homeostasis, this may not be a required event for Al toxicity. The elevation in [Ca2+]c induced by Al also strongly suggests that the phytotoxic action of Al in root hairs is not through blockage of Ca2(+)-permeable channels required for Ca2+ influx into the cytoplasm.

Role of octreotide on release of intact 1-84 parathyroid hormone from human parathyroid cells.

BACKGROUND: Octreotide has been shown to lower urinary calcium in primary hyperparathyroidism although the mechanism remains unclear. This study examined the effect of octreotide on parathyroid hormone (PTH) secretion from human parathyroid cells in culture and as isolated cells. Additionally in situ hybridization was performed for somatostatin receptor messenger RNA (mRNA) and immunocytochemistry for somatostatin in eight parathyroid adenomas. METHODS: Tissue from three hyperplastic glands and three adenomas was studied as dispersed cell suspensions. Incubation was in buffers containing high (2.0 mmol/l) and low (0.5 mmol/l) calcium concentrations, with or without octreotide 200 ng/ml. Cells were also seeded into tissue culture wells for 24 h to allow receptors to regenerate. Supernatant was removed at regular intervals and PTH levels were estimated using a two-site chemiluminescent assay. RESULTS: Mean(s.e.m.) PTH secretion at 90 min in hyperplastic cells was 445(75) pmol/l in low calcium and 160(42) pmol/l in high calcium (P< 0.02), and in adenoma cells was 170(21) pmol/l in low calcium and 137(27) pmol/l in high calcium (P=0.37). There was no significant difference in secretion of PTH from cells incubated with octreotide either in culture or as dispersed cells. In situ hybridization failed to demonstrate any mRNA for the somatostatin receptors and no somatostatin was detected in any cells with immunocytochemistry. CONCLUSION: Somatostatin has no direct action on PTH production and release from human parathyroid cells and is unlikely to be of any therapeutic value in the treatment of hyperparathyroidism.

The high-risk sexual practices of crack-smoking sex workers recruited from the streets of three American cities. The Multicenter Crack Cocaine and HIV Infection Study Team.

BACKGROUND AND OBJECTIVES: Small ethnographic and clinic-based studies indicate that crack-smoking sex workers are at high risk for human immunodeficiency virus (HIV) and sexually transmitted diseases (STD). STUDY GOALS: To examine the prevalence of risky sexual behaviors and HIV and STD in a large sample of street-recruited crack-smoking sex workers. STUDY DESIGN: From 1991 to 1992, 419 crack-smoking sex workers were recruited from urban neighborhoods, interviewed, and serologically tested. RESULTS: Many female and male sex workers reported sex with injectors (30% to 41%) or HIV-infected persons (8% to 19%), past STD (73% to 93%), and inconsistent condom use (> 50% for all types of sex). Sex workers who worked in crack houses or vacant lots, were paid with crack, or injected drugs had the riskiest sex practices. Most sex workers initiated sex work before they first smoked crack. More than 25% were infected with HIV (27.9%), syphilis (37.5%), or herpes simplex virus type 2 (66.8%). CONCLUSIONS: Interventions to prevent HIV/STD transmission among crack-smoking sex workers are urgently needed.