The effects of intracellular pH changes on resting cytosolic calcium in voltage-clamped snail neurones

We have investigated the effects of changing intracellular pH on intracellular free calcium concentration ([Ca2+]i) in voltage-clamped neurones of the snail Helix aspersa. Intracellular pH (pHi) was measured using the fluorescent dye 8-hydroxypyrene-1,3,6-trisulphonic acid (HPTS) and changed using weak acids and weak bases. Changes in [Ca2+]i were recorded using either fura-2 or calcium-sensitive microelectrodes. Acidification of the neurones with 5 mM or 20 mM propionate (approximately 0.2 or 0.3 pH units acidification, respectively) caused a small reduction in resting [Ca2+]i of 5 +/- 2 nM (n = 4) and 7 +/- 16 nM (n = 4), respectively. The removal of the 20 mM propionate after approximately 40 min superfusion resulted in an alkalinization of approximately 0.35 pH units and an accompanying rise in resting [Ca2+]i of 31 +/- 9 nM (n = 4, P < 0.05). The removal of 5 mM propionate did not significantly affect [Ca2+]i. Alkalinizations of approximately 0.2-0.4 pH units of Helix neurones induced by superfusion with 3 mM concentrations of the weak bases trimethylamine (TMA), ammonium chloride (NH4Cl) and procaine were accompanied by significant (P < 0.05) increases in resting [Ca2+]i of 42 +/- 4 nM (n = 26), 30 +/- 7 nM (n = 5) and 36 +/- 4 nM (n = 3), respectively. The effect of TMA (0.5-6 mM) on [Ca2+]i was dose dependent with an increase in [Ca2+]i during pHi increases of less than 0.1 pH units (0.5 mM TMA). Superfusion of neurones with zero calcium (1 mM EGTA) Ringer solution inhibited depolarization-induced calcium increases but not the calcium increase produced by the first exposure to TMA (3 mM). In the prolonged absence of extracellular calcium (approximately 50 min) TMA-induced calcium rises were decreased by 64 +/- 10% compared to those seen in the presence of external calcium (P < 0.05). The calcium rise induced by TMA (3 mM) was reduced by 60 +/- 5% following a 10 min period of superfusion with caffeine (10 mM) to deplete the endoplasmic reticulum (ER) stores of calcium (P < 0.05). Cyclopiazonic acid (10-30 microM CPA), an inhibitor of the ER calcium pump, inhibited the calcium rise produced by TMA (3 mM) and NH4Cl (3 mM) by 61 +/- 4% compared to controls (P < 0.05). These data are consistent with physiological intracellular alkaline shifts stimulating release of calcium, or inhibiting re-uptake of calcium by an intracellular store. The calcium increase was much reduced following application of caffeine, treatment with CPA or prolonged removal of external calcium. Hence the ER was likely to be the source of mobilized calcium.

Self-reported skin problems among physical processors in the chemical industry in Great Britain

Contact dermatitis is common in the chemical industry. A cross-sectional study was conducted to investigate the prevalence of self-reported skin problems in employees involved in the drying, blending, milling, grinding and filling/bagging end of chemical manufacture in small- to medium-sized contract manufacturing/processing chemical companies in Great Britain. There were several secondary aims. Twenty-three per cent of the employees interviewed reported having had a skin problem in the previous 12 months. Of those reporting problems, 46% were always/nearly always involved in blending and 56% were always/nearly always involved in filling and bagging. These same processes were also more commonly associated with continuous or recurring skin problems. Seventy-five per cent reported a problem involving the upper limbs; most had more than one body area affected. Forty-three per cent had consulted a doctor (67% their general practitioner) and 9% took time off work as a result of their skin condition. Skin problems seemed to peak (34% employees) in those who had spent between 1 and 2 years in their current job. Solvents, known skin irritants, were the most frequent, single category of chemicals encountered in the study. Over 92% had been told how to avoid skin problems; 85% reported that they always/almost always wore protective clothing. Despite these measures, a significant number had reported having had a skin problem related to their work in the previous 12 months. Particular attention to control measures based on risk assessment is recommended for these physical processors in the chemical industry. Further research is also recommended into the whole area of personal protective clothing and the individual worker's perception of risks to health in the workplace.

Human papillomavirus-11-associated recurrent respiratory papillomatosis is more aggressive than human papillomavirus-6-associated disease

The aim of this study was to determine whether viral type (HPV-6 vs. HPV-11) could predict the clinical course of recurrent respiratory papillomatosis in children. Viral typing, using the polymerase chain reaction, was performed on laryngeal biopsies of 61 patients treated at Children's Hospital of Michigan. HPV-6 was detected in 29 of the patients' biopsies and HPV-11 in 32 biopsies. HPV-11 was more common among the African-American patients than among Caucasians (P = 0.001). Patients with HPV-11 were diagnosed at a younger age (36.2 vs. 48.2 months; P = 0.04) and were more likely to have active disease (P = 0.0311) at the time of this study. They tended to have longer periods of disease activity (8 years vs. 5 years; P = 0.026), required more surgical procedures (42 procedures/patient vs. 13.6; P = 0.02), and more procedures per patient, per year (2.9 vs. 5.3; P = 0.0164). Three of the patients infected with HPV-11 developed invasive papillomatosis and bronchogenic squamous cell carcinoma, and two of these patients died of disease. Our findings suggest that HPV-11 infection confers a more aggressive course to recurrent respiratory papillomatosis.

Comparison of differentiated dendritic cell infiltration of autoimmune and osteoarthritis synovial tissue

OBJECTIVE

Infiltration of rheumatoid arthritis (RA) synovial tissue (ST) by differentiated dendritic cells (DC) is a consistent feature in patients with active disease. However, mononuclear cells (MNC), including DC, may be nonspecifically chemoattracted to inflammatory sites regardless of etiology. Therefore, to evaluate the specificity of ST infiltration by differentiated DC, synovial biopsies from patients with RA, spondylarthropathy (SpA), osteoarthritis (OA), and gout were examined.

METHODS

Formalin-fixed ST sections were analyzed by double immunohistochemical staining for vascularity and infiltration by differentiated DC, lymphocytes, and macrophages.

RESULTS

DC containing nuclear RelB were found in perivascular MNC aggregates from patients with all arthritides studied. Infiltration by differentiated DC was similar in RA and SpA ST, but reduced in OA ST. Differentiated DC were always observed in close association with lymphocytes, and the correlation between these variables suggested that the infiltration of inflammatory sites by DC and lymphocytes was associated.

CONCLUSION

Perivascular infiltration by DC, lymphocytes, and macrophages is nonspecifically related to inflammation, but signals present in RA and SpA ST lead to more intense cellular infiltration and accumulation.

Evaluating the impact of a locality based social policy intervention on mental health: conceptual and methodological issues

Urban regeneration initiatives provide an opportunity for examining the impact of changes in socio-economic circumstances on the mental health of different groups and individuals within localities. This paper sets out the conceptual and methodological bases for evaluating the impact of a population based social policy intervention on mental health. We suggest the need to integrate a range of disciplinary and methodological developments in research on health inequalities in exploring the impact of urban regeneration on mental health. A combination of multi-level modelling, subjective indicators and narrative accounts of individuals about mental health in the context of locality and personal changes are central for developing theories and methods appropriate for exploring the action and interaction of effects operating between structural and individual/agency levels.

Effect of swim taper on whole muscle and single muscle fiber contractile properties

PURPOSE

To examine the changes in whole muscle function and single cell contractile properties of Type I and II muscle fibers from the deltoid muscle of highly trained swimmers before and after a 21-d reduction in training volume (taper).

METHODS

Six college male swimmers (age, 20+/-1 yr; height, 187+/-2 cm, weight, 79+/-3 kg, fat, 7+/-1%) who had been, on average, swimming 6200 m x d(-1) for 5 months before the taper participated in this investigation.

RESULTS

Whole muscle power increased (P < 0.05) 17% and 13% on the swim bench and swim power tests, respectively. Swim times improved by 4% (range: 3.0-4.7%; P < 0.05). There was no change in Type I fiber diameter, whereas Type IIa fibers were 11% larger (P < 0.05) after taper. Peak force (Po) of the Type I fibers was unaffected by the taper but increased (P < 0.05) from 0.63+/-0.02 to 0.82+/-0.05 mN in the IIa fibers. However, the specific force (Po/CSA) of the IIa fibers was unchanged. Shortening velocity (Vo) was 32% and 67% faster (P < 0.05) in the Type I and IIa fibers, respectively. Although Type I fiber power was unaltered, the IIa fibers increased 2.5-fold from 24.6+/-2.8 to 56.2+/-3.9 microN x FL x s(-1). When power was normalized for cell size, the power was still elevated twofold.

CONCLUSIONS

These data suggest that tapering induces alterations in the contractile properties of single muscle fibers. Further, it appears that the Type IIa fibers are more affected than the Type I fibers by the taper. The increased size, strength, velocity, and power of the IIa fibers may be responsible for the improvements in whole muscle strength and power after the taper.

Dynamics of three-body breakup in dissociative recombination: H(2)O(+)

To better understand the propensity for the three-body breakup in dissociative recombination (DR) of dihydrides ( H(3)(+), NH(2)(+), CH(2)(+), and H(2)O(+)), we undertook a study of the dynamics of this process. A study of DR of H(2)O(+) to give O + H + H was carried out at the CRYRING Heavy-Ion Storage Ring in Stockholm. With the stored beam energy of 4.5 MeV, we separated the O signal from the H signals with a differential absorber, thus reducing the problem to a sum of two two-body problems. Results included (1) the ratio of O((3)P) to O((1)D) product, (2) the distribution of recoil-kinetic energy between the two hydrogen atoms, (3) the angular distribution between the hydrogen atoms in the O((3)P) channel and in the O((1)D) channel.

Use of pattern standard deviation instead of corrected pattern standard deviation in Anderson's criteria

PURPOSE

To determine whether the use of pattern standard deviation instead of corrected pattern standard deviation, as part of Anderson's criteria, makes a difference in categorizing a single field printout using the full threshold strategy on the Humphrey's Field Analyzer.

MATERIALS AND METHODS

Forty-eight patients with glaucomatous field defects of varying severity underwent full threshold perimetry on the Humphrey's Field Analyzer. The third field of one eye was used for the study. The agreement between CPSD and PSD alone was determined. Each field was then categorized using Anderson's criteria first using CPSD and then PSD. The kappa statistic was used to determine agreement in both situations.

RESULTS

The agreement between CPSD and PSD alone, as determined by kappa, was 0.77. The kappa statistic for categorization using Anderson's criteria was 0.82; the weighted kappa was 0.92.

CONCLUSION

There was almost perfect agreement using the PSD instead of CPSD as part of Anderson's criteria. This substitution seems valid for the spectrum of field defects used in this series, at least for the full threshold programs.

Comparison of optical and ultrasound pachometry

PURPOSE

(1) To determine the agreement between optical and ultrasound pachometry for central corneal thickness measurements used to "correct" applanation intraocular pressure (IOP) readings. (2) To determine the inter- and intra-observer variability of optical and ultrasound pachometry.

METHOD

Central corneal thickness (CCT) was measured in a masked manner using optical and ultrasound pachometry in 50 normal eyes. To assess intra- and inter-observer variability, multiple masked measurements were obtained in 51 eyes (optical pachometry) and 34 eyes (ultrasound pachometry). Agreement was determined by a published technique that uses the mean of the differences, standard error (SE) and standard deviation (SD).

RESULTS

The mean difference in CCT between optical and ultrasound pachometry was 0.001 mm (SD 0.031 mm; SE 0.00439 mm). The mean inter-observer difference for the optical pachometer was 0.019 mm (SD 0.049 mm; SE 0.0069); the mean intra-observer difference was 0.003 mm (SD 0.017; SE 0.0.0024). The mean inter-observer difference for ultrasound pachometry was 0.001 mm (SD 0.009; SE 0.0015) and the mean intra-observer difference was 0.002 mm (SD 0.011; SE 0.0019).

CONCLUSIONS

Ultrasound pachometry is the more reliable method for the measurement of central corneal thickness used to correct applanation IOP values. Optical pachometry had good intra-observer variability. The range of error in IOP correction for corneal thickness (inter-observer) that can occur using the ultrasound pachometer is -1.2 mmHg to +1.4 mmHg as compared to -5.6 mmHg to +8.5 mmHg with the optical pachometer.

Successful defibrillation in profound hypothermia (core body temperature 25.6 degrees C)

We report a case of successful defibrillation in a severely hypothermic patient with a core body temperature of 25.6 degrees C as measured oesophageally. Ventricular fibrillation is a recognised life threatening arrhythmia in severely hypothermic patients. The traditional wisdom is that this arrhythmia is refractory to defibrillation at temperatures below 28 degrees C.

Candidate inhibitor of the volume-sensitive kinase regulating K-Cl cotransport: the myosin light chain kinase inhibitor ML-7

K-Cl cotransport, KCC, is activated by swelling in many cells types, and promotes volume regulation by a KCl efflux osmotically coupled to water efflux. KCC is probably activated by swelling-inhibition of a kinase, permitting dephosphorylation, and activation of the cotransporter by a phosphatase. The myosin light chain kinase (MLCK) inhibitor ML-7 inhibits transporters activated by shrinkage. In red blood cells from three mammalian species, ML-7 stimulated KCC in a volume-dependent manner. Relative stimulation was greatest in more shrunken cells. Stimulation was reduced by moderate cell swelling and abolished by further swelling. The half-maximal stimulation is at approximately 20 microm ML-7, 50-fold greater than the IC(50) for inhibition of MLCK in vitro. Stimulation of KCC by ML-7 did not require cell Ca, while MLCK does. Therefore the target of ML-7 in stimulating KCC in red cells is probably not MLCK. The evidence favors stimulation of KCC by ML-7 by inhibiting the volume-sensitive kinase. Qualitatively similar effects of ML-7 on KCC in red cells from three mammalian species suggest a general mechanism.

Recombination of simple molecular ions studied in storage ring: dissociative recombination of H2O+

Dissociative recombination of vibrationally relaxed H2O+ ions with electrons has been studied in the heavy-ion storage ring CRYRING. Absolute cross-sections have been measured for collision energies between 0 eV and 30 eV. The energy dependence of the cross-section below 0.1 eV is found to be much steeper than the E-1 behaviour associated with the dominance of the direct recombination mechanism. Resonant structures found at 4 eV and 11 eV have been attributed to the electron capture to Rydberg states converging to electronically excited ionic states. Complete branching fractions for all dissociation channels have been measured at a collision energy of 0 eV. The dissociation process is dominated by three-body H + H + O breakup that occurs with a branching ratio of 0.71.

RelB nuclear translocation regulates B cell MHC molecule, CD40 expression, and antigen-presenting cell function

Mice with targeted RelB mutations demonstrated an essential role for RelB in immune responses and in myeloid dendritic cell differentiation. Human studies suggested a more global transcriptional role in antigen presentation. Burkitt lymphoma cell lines were used as a model to examine the role of RelB in antigen presentation. After transient transfection of BJAB with RelB, strong nuclear expression of RelB-p50 heterodimers was associated with increased APC function and expression of CD40 and MHC class I. Antisense RelB in DG75 reduced antigen-presenting capacity and CD40-mediated up-regulation of MHC molecules. The data indicate that RelB transcriptional activity directly affects antigen presentation and CD40 synthesis. Stimulation of RelB transcriptional activity may provide a positive feedback loop for facilitating productive APC/T cell interactions.

1999 American Urological Association Gallup Survey: changes in physician practice patterns, treatment of incontinence and bladder cancer, and impact of managed care

PURPOSE

The Health Policy Survey and Research Committee of the American Urological Association and the Gallup Organization have performed a yearly survey of American urologists since 1992 to assess practice patterns. The results of the 1999 survey are presented.

MATERIALS AND METHODS

A random sample of 503 urologists was interviewed in February and March 1999. Major content areas were physician practice patterns, the impact of managed care, and the treatment of pediatric patients, prostate cancer and benign prostatic hyperplasia, female incontinence and bladder cancer.

RESULTS

The average urologist is 46.8 years old, certified by the American Board of Urology, sees 78 patients and performs 3.1 major surgical procedures weekly, refers moderate and complex pediatric procedures to specialists, and receives 40.6% of practice income from managed care.

CONCLUSIONS

In an era when large group practices seem to be the norm remarkably 32% of urologists remain in solo practice. There has been a shift in where urologists spend their time, that is more in the office and less in the operating room. Minor and major open surgical procedures increased from 12.4 weekly to 16.4 and 2.9 to 3.1 in 1995 and 1999, respectively. Most urologists are comfortable treating straightforward pediatric problems such as cryptorchidism but refer more complex problems to pediatric urologists. Managed care represents an ever increasing proportion of urologist practice income, while office expenses continue to increase.

Multiregion contact systems for modelling STD epidemics

This paper elicits properties of some multiregional contact systems for STD infections that are intended to assist the understanding of disease control strategies. To this end, a space-time SIS model is described that maintains the symmetry of contact that is inherent in the formation of sexual partnerships. It is demonstrated how the characteristic stability conditions of this model provide a framework for understanding the potential for sustained transmission after the introduction of the agent into a given region. Then, more complex SI specifications are derived that are particularly relevant to the transmission of HIV. These extensions include the introduction of alternative modes of travel and behavioural adaptations made in response to the circulation of HIV and the incidence of AIDS. The discussion suggests some additions to the systems that might enhance their applicability in practice.

Procalcitonin: a valuable indicator of infection in a medical ICU?

OBJECTIVE

To assess the use of procalcitonin (PCT) for the diagnosis of infection in a medical ICU.

DESIGN

Prospective, observational study.

PATIENTS

Seventy-seven infected patients and 24 patients with systemic inflammatory response syndrome (SIRS) due to other causes. Seventy-five patients could be classified into sepsis (n = 24), severe sepsis (n = 27) and septic shock (n = 24), and 20 SIRS patients remained free from infection during the study. Plasma PCT and C-reactive protein (CRP) levels were evaluated within 48 h of admission (day 0), at day 2 and day 4.

RESULTS

As compared with SIRS, PCT and CRP levels at day 0 were higher in infected patients, regardless of the severity of sepsis (25.2 +/- 54.2 ng/ml vs 4.8 +/- 8.7 ng/ml; 159 +/- 92 mg/l vs 71 +/- 58 mg/l, respectively). At cut-off values of 2 ng/ml (PCT) and 100 mg/l (CRP), sensitivity and specificity were 65% and 70% (PCT), 74% and 74% (CRP). PCT and CRP levels were significantly more elevated in septic shock (38.5 +/- 59.1 ng/ml and 173 +/- 98 mg/l) than in SIRS (3.8 +/- 6.9 ng/ml and 70 +/- 48 mg/l), sepsis (1.3 +/- 2.7 ng/ml and 98 +/- 76 mg/l) and severe sepsis (9.1 +/- 18. 2 ng/ml and 145 +/- 70 mg/l) (all p = 0.005). CRP, but not PCT, levels were more elevated in severe sepsis than in SIRS (p<0.0001). Higher PCT levels in the patients with four dysfunctional organs and higher PCT and CRP levels in nonsurvivors may only reflect the marked inflammatory response to septic shock.

CONCLUSION

In this study, PCT and CRP had poor sensitivity and specificity for the diagnosis of infection. PCT did not clearly discriminate SIRS from sepsis or severe sepsis.