Natural killer cell education in mice with single or multiple major histocompatibility complex class I molecules

The ability of murine NK cells to reject cells lacking self MHC class I expression results from an in vivo education process. To study the impact of individual MHC class I alleles on this process, we generated mice expressing single MHC class I alleles (K^b, D^b, D^d, or L^d) or combinations of two or more alleles. All single MHC class I mice rejected MHC class I–deficient cells in an NK cell–dependent way. Expression of K^b or D^d conveyed strong rejection of MHC class I–deficient cells, whereas the expression of D^b or L^d resulted in weaker responses. The educating impact of weak ligands (D^b and L^d) was further attenuated by the introduction of additional MHC class I alleles, whereas strong ligands (K^b and D^d) maintained their educating impact under such conditions. An analysis of activating and inhibitory receptors in single MHC class I mice suggested that the educating impact of a given MHC class I molecule was controlled both by the number of NK cells affected and by the strength of each MHC class I–Ly49 receptor interaction, indicating that NK cell education may be regulated by a combination of qualitative and quantitative events.

Low levels of CC16 in nasal fluid of children with birch pollen-induced rhinitis

BACKGROUND

Clara cell protein 16 (CC16; secretoglobin 1A1) is an anti-inflammatory protein mainly expressed in the epithelial cells in the airways.

OBJECTIVE

To compare the levels of CC16 in nasal lavage (NAL) from children with intermittent allergic rhinitis and healthy controls and to study the effect of a local steroid.

METHODS

Thirty schoolchildren with birch pollen allergy and 30 healthy controls from the same schools were included in the study. The NAL fluid was collected before the season, during the birch pollen season and, for the patients, after 1 week of treatment with a local steroid. Symptom scores were obtained on every occasion. CC16 and eosinophil cationic protein (ECP) were analyzed with enzyme-linked immunosorbent assay.

RESULTS

The nasal fluid levels of CC16 were significantly lower in patients than in controls, before and during pollen season. Before the season, the median CC16 concentrations were 9.1 (range 1.1-117) microg/l in patients and 25.7 (6.1-110.2) microg/l in controls. During the season, the median CC16 concentrations in nasal fluid were 12.9 (2.3-89.7) microg/l in the allergic children and 22.0 (9.5-90.1) microg/l in the healthy controls (P = 0.0005). Symptom scores, nasal fluid eosinophils and ECP were higher in patients during the season. Treatment with a local steroid did not change the CC16 levels.

CONCLUSIONS

Nasal fluid CC16 levels were lower in children with birch pollen-induced allergic rhinitis than in healthy controls both before and during the pollen season. We speculate that reduction in anti-inflammatory activity by CC16 may contribute to the pathogenesis of allergic rhinitis.

The oral direct thrombin inhibitor, ximelagatran, an alternative for anticoagulant treatment during the puerperium and lactation

OBJECTIVE

To determine the excretion of the oral direct thrombin inhibitor (oral DTI), ximelagatran, and its active form, melagatran, in human milk, and to thus evaluate the potential exposure of breastfed infants to melagatran.

DESIGN

An open, single dose, single centre study.

SETTING

Department of Antenatal Care, Primary Health Care South Bohuslän and Institute for the Health of Women and Children, Göteborg University, Sweden.

SAMPLE

Seven healthy Caucasian breastfeeding women who were at least two months postpartum were studied.

METHODS

The concentrations of ximelagatran, its two intermediates, and melagatran were determined using liquid chromatography-mass spectrometry, with the limit of quantification of 2 nmol L(-1) for human milk and 10 nmol L(-1) for plasma concentrations.

MAIN OUTCOME MEASURES

Concentrations of ximelagatran, its intermediates and melagatran were measured in breast milk over 72 hours, and in plasma over 12 hours, after a single oral 36 mg dose of ximelagatran.

RESULTS

Neither ximelagatran nor its intermediates were detected in human breast milk. Only trace amounts of melagatran were detected. The mean cumulative amount of melagatran excreted into breast milk over the 72-hour period after dosing with oral ximelagatran was 0.00091% of the administered dose of ximelagatran. Ximelagatran was well tolerated, with no clinically relevant changes in laboratory variables or vital signs.

CONCLUSIONS

Trace levels of melagatran are excreted in human breast milk following administration of the oral DTI ximelagatran. The exposure of breastfed infants to melagatran appears to be low and is therefore unlikely to be of clinical concern.

Epidemiology of gastro-oesophageal reflux disease: a systematic review

A systematic review of the epidemiology of gastro-oesophageal reflux disease (GORD) has been performed, applying strict criteria for quality of studies and the disease definition used. The prevalence and incidence of GORD was estimated from 15 studies which defined GORD as at least weekly heartburn and/or acid regurgitation and met criteria concerning sample size, response rate, and recall period. Data on factors associated with GORD were also evaluated. An approximate prevalence of 10-20% was identified for GORD, defined by at least weekly heartburn and/or acid regurgitation in the Western world while in Asia this was lower, at less than 5%. The incidence in the Western world was approximately 5 per 1000 person years. A number of potential risk factors (for example, an immediate family history and obesity) and comorbidities (for example, respiratory diseases and chest pain) associated with GORD were identified. Data reported in this systematic review can be interpreted with confidence as reflecting the epidemiology of "true" GORD. The disease is more common in the Western world than in Asia, and the low rate of incidence relative to prevalence reflects its chronicity. The small number of studies eligible for inclusion in this review highlights the need for global consensus on a symptom based definition of GORD.

Epidemiology of gastro-oesophageal reflux disease: a systematic review

A systematic review of the epidemiology of gastro-oesophageal reflux disease (GORD) has been performed, applying strict criteria for quality of studies and the disease definition used. The prevalence and incidence of GORD was estimated from 15 studies which defined GORD as at least weekly heartburn and/or acid regurgitation and met criteria concerning sample size, response rate, and recall period. Data on factors associated with GORD were also evaluated. An approximate prevalence of 10-20% was identified for GORD, defined by at least weekly heartburn and/or acid regurgitation in the Western world while in Asia this was lower, at less than 5%. The incidence in the Western world was approximately 5 per 1000 person years. A number of potential risk factors (for example, an immediate family history and obesity) and comorbidities (for example, respiratory diseases and chest pain) associated with GORD were identified. Data reported in this systematic review can be interpreted with confidence as reflecting the epidemiology of "true" GORD. The disease is more common in the Western world than in Asia, and the low rate of incidence relative to prevalence reflects its chronicity. The small number of studies eligible for inclusion in this review highlights the need for global consensus on a symptom based definition of GORD.

Computational modeling of human natural killer cell development suggests a selection process regulating coexpression of KIR with CD94/NKG2A

Natural killer cells fail to lyse target cells expressing sufficient levels of self MHC class I molecules, providing one mechanism to secure self tolerance. Inhibition of lysis is mediated by inhibitory receptors expressed by NK cells, such as the murine Ly49 receptors, human KIR receptors and CD94/NKG2A, expressed by both species. To ensure that most, if not all, NK cells express at least one inhibitory receptor for self MHC class I, selection processes have been postulated for murine NK cells regulating the number and identity of inhibitory receptors expressed by each cell. The presence of similar selection processes in human NK cells has not been demonstrated. In previous studies using mathematical modeling we have shown that, in the Ly49 system, the sequential model (in which gene expression and selection operate simultaneously) is most likely to explain the observed expression frequencies. We also predicted the parameters (such as receptor-ligand binding affinity levels) under which the models fit with the observed frequencies. This study aims to evaluate whether these models may be valid in the human system. Our data suggest that if selection operates during human NK cell development, it affects the co-expression of CD94/NKG2A and KIR rather than KIR expression alone, and is more likely to be governed by the two-step selection model.

Effects of perinatal asphyxia on cell survival, neuronal phenotype and neurite growth evaluated with organotypic triple cultures

The effect of perinatal asphyxia on brain development was studied with organotypic cultures from substantia nigra, neostriatum and neocortex. Asphyxia was induced by immersing foetuses-containing uterine horns removed from ready-to-deliver rats into a water bath for 20 min. Following asphyxia, the pups were nursed by a surrogate dam and sacrificed after three days for preparing organotypic cultures. Non-asphyxiated caesarean-delivered pups were used as controls. Morphological features and cell viability were recorded during in vitro development. At day in vitro (DIV) 24, the cultures were treated for immunocytochemistry using antibodies against the N-methyl-D-aspartate receptor subunit 1 (NR1) and tyrosine hydroxylase (TH). While in vitro survival was similar in cultures from both asphyxiated and control animals, differences were observed when the neuronal phenotype was assessed. Compared to controls, the total number of NR1-positive neurons in substantia nigra, as well as the number of secondary to higher level branching of TH-positive neurites from asphyxiated pups were decreased, illustrating the vulnerability of the dopaminergic systems to perinatal asphyxia.

A method of predicting the image noise in paediatric multi-slice computed tomography images

The purpose of this study was to develop an equation with which to determine the tube current to be used in order to obtain a certain image noise level for differently sized children undergoing multi-slice computed tomography examination. The relationship between image noise and detector dose for different examination protocols was established for a LightSpeed Ultra, an eight slice CT from GEMS, using homogeneous water phantoms of different sizes. Three different anatomical areas (head, thorax and abdomen) were studied in 111 patients between 0 and 17 y of age. The mean ratio between the calculated and the measured noise in patient images was established for the different areas. Head examinations showed the best correlation (measured-to-calculated noise ratio = 1.01). In the thorax, the calculated noise was generally higher than the measured noise (ratio = 0.74), and in the abdomen, the opposite result was found (ratio = 1.20).

Serotypes and clinical manifestations of invasive group B streptococcal infections in western Sweden 1998-2001

This study monitored the serotypes of Streptococcus agalactiae (group B streptococcus; GBS) isolated from invasive infections in western Sweden and investigated possible relationships between serotype, age and clinical manifestations. Invasive GBS isolates were collected prospectively during 1998-2001 at six laboratories, covering two counties with a population of 1.8 million, and were serotyped by coagglutination. Clinical data were obtained from hospital notes. In total, 161 invasive strains (50 from neonates and infants aged < 3 months, and 111 from adults) were serotyped. The commonest serotypes from neonates and infants were serotypes III (60%), V (22%) and Ia (10%), and from adults were serotypes V (42%) and III (25%). Serotype V had doubled in frequency among both children and adults compared to a previous study from the same area in 1988-1997. Most (80%) of the adults had an underlying medical condition. No relationship was found between serotype and clinical manifestations. However, the study demonstrated the importance of active surveillance of GBS serotypes and the difficulties of formulating a multivalent polysaccharide conjugate vaccine against GBS.

Natural history of gastro-oesophageal reflux disease diagnosed in general practice

BACKGROUND

Cross-sectional studies indicate that gastro-oesophageal reflux disease symptoms have a prevalence of 10-20% in Western countries and are associated with obesity, smoking, oesophagitis, chest pain and respiratory disease.

AIM

To determine the natural history of gastro-oesophageal reflux disease presenting in primary care in the UK.

METHODS

Patients with a first diagnosis of gastro-oesophageal reflux disease during 1996 were identified in the UK General Practice Research Database and compared with age- and sex-matched controls. We investigated the incidence of gastro-oesophageal reflux disease, potential risk factors and comorbidities, and relative risk for subsequent oesophageal complications and mortality.

RESULTS

The incidence of a gastro-oesophageal reflux disease diagnosis was 4.5 per 1000 person-years (95% confidence interval: 4.4-4.7). Prior use of non-steroidal anti-inflammatory drugs, smoking, excess body weight and gastrointestinal and cardiac conditions were associated with an increased risk of gastro-oesophageal reflux disease diagnosis. Subjects with gastro-oesophageal reflux disease had an increased risk of respiratory problems, chest pain and angina in the year after diagnosis, and had a relative risk of 11.5 (95% confidence interval: 5.9-22.3) of being diagnosed with an oesophageal complication. There was an increase in mortality in the gastro-oesophageal reflux disease cohort only in the year following the diagnosis.

CONCLUSIONS

Gastro-oesophageal reflux disease is a disease associated with a range of potentially serious oesophageal complications and extra-oesophageal diseases.

Vitamin A differentially regulates RANKL and OPG expression in human osteoblasts

All-trans-retinoic acid (ATRA) induces bone resorption, but the molecular mechanisms are unknown. We have studied the effect of ATRA on osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) expression in human MG-63 osteosarcoma cells and primary osteoblast-like cultures. ATRA dose-dependently down-regulated protein levels of OPG in MG-63 cells, with a maximum (-56%) observed at a dose of 10(-6)M. This effect was confirmed with quantitative real-time PCR, where OPG mRNA was decreased after 4h (-68%) in primary cultures and after 8h (-87%) in MG-63 cells. The reduction in OPG expression was inhibited by a retinoic acid receptor (RAR)-antagonist and was mimicked by a RARbeta,gamma-agonist, indicating that the ATRA effect is mediated by these receptors. In primary cultures we found a threefold induction of RANKL mRNA expression. Thus, the RANKL/OPG ratio was markedly increased, suggesting a potential mechanism of ATRA-induced bone resorption.

Loss or mismatch of MHC class I is sufficient to trigger NK cell-mediated rejection of resting lymphocytes in vivo - role of KARAP/DAP12-dependent and -independent pathways

A prediction from the "missing self" hypothesis is that down-regulation of MHC class I on resting hematopoietic cells should be sufficient to make them susceptible to NK cell killing. Using a method enabling kinetic and quantitative assessments of NK cell-mediated rejection responses in vivo, we here show that resting hematopoietic cells from beta(2)-microglobulin-deficient (beta(2)m(-/-)) mice were rapidly rejected in unmanipulated C57BL/6 (B6) mice. In situations of allelic MHC class I mismatches rejection occurred but required longer time. beta(2)m(-/-) donor cells pre-activated with concanavalin A were more efficiently eliminated compared to resting cells, as were MHC(-) tumor cells. When recipient mice were pretreated with an IFN inducer to activate NK cells, rejection was also enhanced. The signaling adaptor KARAP/DAP12 was dispensable for rejection of beta(2)m(-/-) cells (lacking MHC) but critical for rejection of BALB/c cells (mismatched MHC) in unmanipulated B6 recipients. In contrast, B6 recipients with pre-activated NK cells rejected BALB/c cells in a KARAP/DAP12-independent fashion. Loss or mismatch of MHC class I in resting cells was thus sufficient to convey susceptibility to NK cell rejection. However, activation of the effector or the target enhanced rejection and shifted the balance between different signaling pathways involved.

Nocturia and depression

OBJECTIVE

To assess the possible relationship between major depression (MD) and nocturia.

SUBJECTS AND METHODS

An unselected group of adult men and women, living in the city of Ostersund, Sweden, were sent a postal questionnaire containing questions on somatic and mental health, sleep, sleepiness and nocturia. For depression diagnostics the Major Depression Inventory (MDI) was used.

RESULTS

The mean (sd) ages of the men and women were 48.0 (18.2) and 50.1 (19.1) years, respectively. Two or more nocturnal micturition episodes occurred in 15.6% of the men and 16.5% of the women. In a multiple logistic regression analysis independent correlates (with 95% confidence intervals) for >/= 2 nocturnal voids in men were: MD 6.5 (2.6-15.6); health, fair vs good, 1.8 (1.0-3.9); health, poor vs good, 2.7 (1.1-4.8); age, 60-74 vs 18-29, 3.6 (1.5-8.4) and age >/= 75 vs 18-29 6.7 (2.6-17.4); and in women: MD 2.8 (1.3-6.3); health, fair vs good, 1.9 (1.1-3.2); health, poor vs good, 4.3 (2.6-8.2); age, 60-74 vs 18-29, 3.8 (1.8-7.8), and age >/= 75 vs 18-29, 8.6 (4.0-18.6). Age < 60 years was deleted by the logistic model in both sexes.

CONCLUSION

MD is associated with a six-fold increase in nocturia in men and a three-fold increase in women, after accounting for age and health. Possible pathogenetic mechanisms of this relationship may involve both increased nocturnal diuresis via a disturbed 24-h rhythm of antidiuretic hormone secretion, and a decrease in nocturnal bladder capacity through a central and/or peripheral serotonergic effect.

Increased levels of triglycerides, BMI and blood pressure and low physical activity increase the risk of diabetes in Swedish women. A prospective 18-year follow-up of the BEDA study

AIM

To investigate risk factors for the development of diabetes in middle-aged women.

METHODS

A random population sample of 1351 women without prior diabetes or cardiovascular disease, aged 39-65 years, took part in a screening study in 1979-1981 with questionnaires, physical examination and blood sampling. Development of diabetes up to 1998 was identified at a second examination in 1997-1998.

RESULTS

Seventy-three women (5.4%) were diagnosed with diabetes during follow-up. As expected, obesity resulted in a rising age-adjusted risk with hazards ratio 3.2 [95% confidence interval (CI) 1.3, 8.1] at body mass index (BMI) 24-27 kg/m(2), and 8.3 (3.5, 19.7), at BMI > or = 27, compared with BMI < 22 kg/m(2). S-triglycerides (TG) carried a steeply increasing age-adjusted risk with hazards ratio 4.0 (95% CI 2.1, 7.6) already at s-TG 1.0-1.4 mmol/l, 7.1 (3.6, 14.0) at s-TG 1.5-1.9 mmol/l and 9.3 (4.3, 20.2) at s-TG > or = 2.0 mmol/l compared with s-TG < 1.0 mmol/l. Increasing systolic blood pressure (SBP) to 130-144, 145-159 and > or = 160 mmHg escalated the hazards ratio of diabetes to 1.6 (0.8, 3.3), 3.6 (1.7, 7.4) and 5.6 (2.7, 11.4), respectively, compared with SBP < 130 mmHg. Also, low physical activity predicted diabetes, with hazards ratio 2.1 (1.3, 3.3) for sedentary compared with non-sedentary activity. Smoking was not associated with increased risk of diabetes. After adjustment for BMI, SBP and physical activity, increasing TG level remained a strong and significant risk factor for diabetes [hazards ratio 3.0 (1.6, 5.7), 3.7 (1.8, 7.7) and 4.5 (2.0, 10.0), P < 0.001].

CONCLUSIONS

Among middle-aged Swedish women even very slightly elevated s-TG resulted in a considerably enhanced risk of developing diabetes, which was independent of age, BMI, blood pressure and physical activity.

Coffee and incidence of diabetes in Swedish women: a prospective 18-year follow-up study

OBJECTIVES

To examine the long-term incidence of diabetes in relation to coffee consumption in Swedish women.

DESIGN

Prospective longitudinal cohort study.

SETTING

City of Göteborg, Sweden.

SUBJECTS

A random population sample of 1361 women, aged 39-65 years, without prior diabetes or cardiovascular disease took part in a screening study in 1979-1981 with questionnaires, physical examination and blood sampling.

MAIN OUTCOME MEASURES

The development of diabetes until 1999 was identified by questionnaires in a second screening and the Swedish hospital discharge register.

RESULTS

Altogether, there were 74 new cases of diabetes. The risk of developing diabetes was 475 per 100 000 person-years in women who consumed two cups of coffee or less per day, 271 in women who consumed three to four cups per day, 202 with a consumption of five to six cups per day, and 267 in drinkers of seven cups or more per day. Associated hazard ratios, after adjustment for age, smoking, low physical activity, education and body mass index were 0.55 (0.32-0.95), 0.39 (0.20-0.77) and 0.48 (0.22-1.06) for daily consumption of three to four, five to six and seven cups or more, respectively, with a consumption of less than two per day as reference. Additional adjustment for serum cholesterol and triglycerides attenuated the relation between coffee and diabetes slightly, indicating a possible mediating effect on the effect of coffee by serum lipids.

CONCLUSIONS

The findings of the present study support the hypothesis that coffee consumption protects from the development of diabetes in women.

Is there any association between myocardial infarction, gastro-oesophageal reflux disease and acid-suppressing drugs?

BACKGROUND

A link between gastro-oesophageal reflux disease and coronary heart disease has been suggested.

AIM

To estimate the incidence of myocardial infarction in patients with newly diagnosed gastro-oesophageal reflux disease in comparison with that in the general population.

METHODS

A population-based cohort study was performed in the UK. Patients aged 18-79 years with a first diagnosis of gastro-oesophageal reflux disease (n = 7084) were identified and a group of 10,000 patients free of gastro-oesophageal reflux disease were sampled. A nested case-control analysis was performed to assess the risk factors for myocardial infarction.

RESULTS

The incidence of myocardial infarction in the general population was 4.0 per 1,000 person-years [95% confidence interval (CI), 3.2-4.9] and 5.1 per 1,000 person-years (95% CI, 4.1-6.4) in patients with gastro-oesophageal reflux disease. The relative risk of myocardial infarction in patients with gastro-oesophageal reflux disease was 1.4 (95% CI, 1.0-1.9). The increased risk of myocardial infarction was limited to the immediate days after the diagnosis of gastro-oesophageal reflux disease. Previous chest pain was an important predictor of myocardial infarction in patients free of gastro-oesophageal reflux disease. No association was found between the use of acid-suppressing drugs and the risk of myocardial infarction.

CONCLUSION

Our results suggest that gastro-oesophageal reflux disease is not an independent predictor of myocardial infarction. Rather, the increased risk of myocardial infarction in patients with gastro-oesophageal reflux disease in the immediate days after diagnosis indicates that prodromal ischaemic symptoms were misinterpreted as reflux symptoms.

Perinatal asphyxia impairs connectivity and dopamine neurite branching in organotypic triple culture from rat substantia nigra, neostriatum and neocortex

The effect of perinatal asphyxia on brain development was studied with organotypic cultures from substantia nigra, neostriatum and neocortex. Asphyxia was induced by immersing foetuses-containing uterine horns removed from ready-to-deliver rats into a water bath for 20 min. Following asphyxia, the pups were nursed by a surrogate dam and sacrificed after 3 days to prepare organotypic cultures. Non-asphyxiated caesarean-delivered pups were used as controls. Morphological features were recorded during in vitro development. At day in vitro (DIV) 24, the cultures were treated for histochemistry using fast red for cell nucleus labelling and antibodies against tyrosine hydroxylase for dopaminergic neurons. Compared to controls, cultures from asphyxiated pups revealed a diminished integration quantified during 21 DIV. After immunocytochemistry and camera lucida reconstruction, tyrosine hydroxylase-positive neurons showed a decreased number of neurites from secondary and higher level branching, demonstrating a vulnerability of the dopaminergic systems after perinatal asphyxia.

HLA associations in type 1 diabetes: DPB1 alleles may act as markers of other HLA-complex susceptibility genes

Alleles at the HLA-DQB1, -DQA1 and -DRB1 loci are major determinants for susceptibility to develop type 1 diabetes (T1D). Increasing evidence supports that also other genes in, or near, the HLA complex contribute to the HLA-encoded risk. Alleles at the DPB1 locus have been suggested to directly influence the risk conferred by DQB1, DQA1 and DRB1 alleles, but the results are conflicting. We therefore genotyped 217 families from Norway, Denmark, Sweden and southern France to address the role of DPB1 alleles in T1D. After taking into account linkage disequilibrium (LD) with DQB1, DQA1 and DRB1 alleles, we found evidence that some DPB1 alleles are associated with modulating the risk of developing T1D. However, we show that the strong LD in the HLA complex, and the presence of extended haplotypes complicate the interpretation of the results. On DQ2-DR3 haplotypes, both allele 3 at microsatellite D6S2223 located 5.3-Mb telomeric of DPB1 and the extended DQ2-DR3-B18 haplotype display much stronger association than DPB1 alleles. When we exclude these effects, most of the apparent association of DPB1 alleles on DQ2-DR3 haplotypes disappear. Taken together, although we cannot completely rule out an effect of some DPB1 alleles, we propose that the statistically significant, albeit weak, DPB1 associations found are most likely the result of LD with another unidentified disease-susceptibility gene(s) in this region.

Perinatal water intoxication due to excessive oral intake during labour

The increased body water in pregnant women and the birth-related activation of water-sparing systems contribute to a high risk of perinatal water intoxication if the mother drinks too much water during labour. This study reports on four newborn term infants and one mother presenting with life-threatening symptoms due to hyponatraemia from excessive oral intake during labour. Awareness of this diagnosis in the delivery unit is very important, because the clinical picture may mimic that of pre-eclampsia or dehydration.

CONCLUSION

Guidelines are proposed to prevent and treat perinatal water intoxication due to excessive oral intake during labour.

Radiative cycle with stimulated emission from atoms and ions in an astrophysical plasma

We propose that a radiative cycle operates in atoms and ions located in a rarefied gas in the vicinity of a hot star. Besides spontaneous transitions the cycle includes a stimulated transition in one very weak intermediate channel. This radiative "bottleneck" creates a population inversion, which for an appropriate column density results in amplification and stimulated radiation in the weak transition. The stimulated emission opens a fast decay channel leading to a fast radiative cycle in the atom (or ion). We apply this model by explaining two unusually bright Fe II lines at 250.7 and 250.9 nm in the UV spectrum of gas blobs close to eta Carinae, one of the most massive and luminous stars in the Galaxy.

Small, novel proteins from the mistletoe Phoradendron tomentosum exhibit highly selective cytotoxicity to human breast cancer cells

Four novel proteins (phoratoxins C-F) have been isolated from the North American mistletoe Phoradendron tomentosum. The amino acid sequences of these phoratoxins were determined unambiguously using a combination of Edman degradation and trypsin enzymatic digestion, and by electrospray ionization tandem mass spectrometry sequencing. Phoratoxins C, E and F consist of 46 amino acid residues; and phoratoxin D of 41. All proteins had six cysteines, similar to the earlier described phoratoxins A and B, which are thionins. The cytotoxicity of each protein was evaluated in a human cell line panel that represented several cytotoxic drug-resistance mechanisms. For the half-maximal inhibitory concentrations (IC50 values) of the different cell lines in the panel, correlation with those of standard drugs was low. The most potent cytotoxic phoratoxin C was further tested on primary cultures of human tumor cells from patients. The solid tumor samples from breast cancer cells were 18 times more sensitive to phoratoxin C than the tested hematological tumor samples.

Evidence of at least two type 1 diabetes susceptibility genes in the HLA complex distinct from HLA-DQB1, -DQA1 and -DRB1

Susceptibility to, and protection against development of type 1 diabetes (T1D) are primarily associated with the highly polymorphic exon 2 sequences of the HLA class II genes: DQB1, DQA1 and DRB1. However, several studies have also suggested that additional genes in the HLA complex influence T1D risk, albeit to a lesser degree than the class II genes. We have previously shown that allele 3 of microsatellite marker D6S2223, 4.9 Mb telomeric of DQ in the extended class I region, is associated with a reduction in risk conferred by the DQ2-DR3 haplotype. Here we replicate this finding in two populations from Sweden and France. We also show that markers in the HLA class II, III and centromeric class I regions contribute to the DQ2-DR3 associated risk of T1D, independently of linkage disequilibrium (LD) with both the DQ/DR genes and the D6S2223 associated gene. The associated marker alleles are carried on the DQ2-DR3-B18 haplotype in a region of strong LD. By haplotype mapping, we have located the most likely location for this second DQ2-DR3 haplotype-modifying locus to the 2.35 Mb region between HLA-DOB and marker D6S2702, located 970 kb telomeric of HLA-B.

Subclinical hypervitaminosis A causes fragile bones in rats

Excessive intake of vitamin A has been associated with an increased risk of hip fracture in humans. This finding has raised the question of whether long-term intake of relatively moderate doses ("subclinical" hypervitaminosis A) contributes to fracture risk. Although it has been known for more than half a century that toxic doses of vitamin A lead to spontaneous fractures in rats, the lowest intake that induces adverse effects is not known, and the result of exposure to excessive doses that do not cause general toxicity has been rarely investigated. In this study, mature female rats were fed a standard diet with 12 IU vitamin A/g pellet (control, C), or standard diet supplemented with either 120 IU ("10 x C") or 600 IU ("50 x C") vitamin A/g pellet for 12 weeks. Fifteen animals were included in each group. The supplemented diets correspond to a vitamin A intake of approximately 1800 IU/day and 9000 IU/day, respectively. The latter dose is about one third of that previously reported to cause skeletal lesions. At the end of the study, serum retinyl esters were elevated 4- (p < 0.01) and 20-fold (p < 0.001) and the total amount of liver retinoid had increased 3- (p < 0.001) and 7-fold (p < 0.001) in the 10 x C and 50 x C group, respectively. The animals showed no clinical signs of general toxicity, and there were no significant bone changes in the 10 x C group. However, in the 50 x C group, a characteristic thinning of the cortex (cortical area -6.5% [p < 0.001]) and reduction of the diameter of the long bones were evident (bone cross-sectional area -7.2% [p < 0.01] at the midshaft and -11.0% [p < 0.01] at the metaphysis), as measured by peripheral quantitative computed tomography. In agreement with these data and a decreased polar strength strain index (-14.0%, p < 0.01), the three-point bending breaking force of the femur was reduced by 10.3% (p < 0.01) in the 50 x C group. These data indicate that the negative skeletal effects appear at a subchronic vitamin A intake of somewhere between 10 and 50 times the standard diet. This level is considerably lower than previously reported. Our results suggest that long-term ingestion of modest excesses of vitamin A may contribute to fracture risk.

Glutamate-induced currents reveal three functionally distinct NMDA receptor populations in rat dorsal horn - effects of peripheral nerve lesion and inflammation

The importance of the N-methyl-D-aspartate (NMDA) receptor in various painful conditions is well established. The effects of peripheral nerve lesion or joint inflammation, as models of different pain states, on NMDA receptor-mediated currents and NMDA receptor subunit mRNA expression were therefore studied in acutely dissociated neurones from the rat spinal cord dorsal horn. In the neuronal population from control rats, all four NR2 subunits and both NR1 splice variants assayed were detected. A majority of neurones expressed mRNA for more than one NR2 subunit, and some neurones expressed all four NR2 subunits as well as both NR1 splice variants. The NR2B subunit was the most commonly expressed, while the NR2C was the rarest. Following nerve lesion, fewer neurones expressed NR2A compared to the control. The dose-response curve for glutamate-evoked NMDA receptor-mediated currents in the neurones was best described by a three-component fit, suggesting that three functionally distinct NMDA receptor populations are present in the dorsal horn. Minor changes in the dose-response curve after nerve lesion could not be ascribed with certainty to the lesion. Changes in other parameters of NMDA receptor-mediated currents were observed neither after nerve lesion nor after joint inflammation. In summary, the present work demonstrates that single dorsal horn neurones express mRNA for several NMDA receptor subunits. The glutamate dose-response curves indicate that there are three major types of NMDA receptors present in dorsal horn neurones. We also report a reduced expression of NR2A following peripheral nerve lesion.

Gender and drug treatment as determinants of mortality in a cohort of heart failure patients

AIM

We assessed gender differences in the risk of mortality in heart failure (HF) patients and evaluated the association between HF drug treatment and mortality.

METHODS AND RESULTS

We identified a cohort of 820 patients with newly diagnosed HF in 1996 in UK general practices. The diagnosis of HF was confirmed by the general practitioner. Fifty per cent were females and 27% were less than 70 years old. During a mean follow-up of 2 years, 172 patients died. We used computerized records to assess risk factors and drugs prescribed as treatment. The information on severity was assessed through a questionnaire. We performed a nested case-control analysis, and observed that men had twice the risk of dying than females, however the effect of age on mortality was stronger in females than males. We found a similar interaction between HF severity and sex. Data on use of some cardiovascular drugs such as diuretics, beta-blockers ACE-inhibitors and calcium channel blockers were suggestive of a reduced mortality risk. Current use of nitrates and glycosides carried an increased risk.

CONCLUSION

Older age, male sex and severity of HF were the main predictors of mortality among HF patients. Long-term use of beta-blockers was associated with a significantly reduced risk of mortality.

cDNA cloning and sequencing of rat .alpha.1-macroglobulin

cDNA clones coding for the plasma protease inhibitor alpha 1-macroglobulin were isolated from a rat liver library. The obtained cDNA sequence contained 4701 nucleotides and had an open reading frame coding for a 1,500 amino acid long protein, including a 24 amino acid signal peptide. The identity of the deduced protein sequence as alpha 1-macroglobulin was established by comparison with published peptide sequences of the protein. The mature protein shares 53% and 57% overall amino acid identity with the two other identified members of the rat alpha-macroglobulin family, alpha 1-inhibitor 3 and alpha 2-macroglobulin. A sequence typical for an internal thiol ester was identified. Of the 24 cysteines, 23 are conserved with alpha 2-macroglobulin. However, instead of the two most C-terminal cysteines in alpha 2-macroglobulin, which forms a disulfide bridge in the receptor binding domain, alpha 1-macroglobulin contains phenylalanine. One mRNA species hybridizing with the alpha 1-macroglobulin probe was observed in rat and mouse liver RNA (approximately 6.2 kb), whereas no corresponding transcript was detected in RNA from human liver.

Extra-intestinal manifestations associated with irritable bowel syndrome: a twin study

BACKGROUND

Little is known about the role of genetic and environmental factors in irritable bowel syndrome. Various extra-intestinal manifestations are more prevalent in cases than in controls. Genetic effects may be important in the liability to develop functional bowel disorders.

AIMS

To evaluate the associations of irritable bowel syndrome with several disorders co-morbid with the condition, using both a case-control design and a co-twin control design.

METHODS

A sample of 850 Swedish twin pairs, aged 18-85 years, was contacted for a telephone interview. Through a diagnostic algorithm, 72 unrelated cases of irritable bowel syndrome and 216 age- and gender-matched controls were identified. Fifty-eight twin pairs discordant for irritable bowel syndrome were evaluated in co-twin analyses.

RESULTS

Renal problems (odds ratio (OR)=3.3; confidence interval (CI), 1.3-8.2), obesity (OR=2.6; CI, 1.0-6.4), underweight in the past (OR=2.4; CI, 1.1-6.4), gluten intolerance (OR=9.0; CI, 1.4-60.1), rheumatoid arthritis (OR=3.2; CI, 1.1-9.4) and poor self-rated health (OR=1.8; CI, 1.0-3.2) were significantly associated with irritable bowel syndrome. In the co-twin analyses, the only factors maintaining significance were renal and recurrent urinary tract problems.

CONCLUSIONS

The association between irritable bowel syndrome and renal and urinary tract problems does not reflect a genetic or familial mediation. Eating disorders in childhood represent a familial-environmental influence on irritable bowel syndrome, whereas the association with rheumatoid arthritis and perhaps gluten intolerance probably reflects genetic mediation.

Serum IgE reactivity to Malassezia furfur extract and recombinant M. furfur allergens in patients with atopic dermatitis

IgE reactivity to the opportunistic yeast Malassezia furfur can be found in patients with atopic dermatitis (AD). We have previously cloned and expressed 6 recombinant allergens (rMal f 1, rMal f 5-9) from M. furfur. In the present study, we used ImmunoCAP to investigate whether these rMal f allergens can be useful in the diagnosis of M. furfur-associated AD compared with the M. furfur extract. A total of 156 adult patients with a clinical diagnosis of AD participated in the study. Sixty-four percent had increased total serum IgE levels, 79% had specific IgE antibodies to common inhalant allergens and 47% had IgE antibodies to M. furfur extract. IgE antibodies to any of the rMal f allergens were detected among 86 (55%) of the patients, 14 (16%) of whom did not react to the M. furfur extract. Any individual rMal f allergen detected between 32% and 89% of the patients ImmunoCAP-positive to the M. furfur extract, with the highest sensitivity for rMal f 9. Therefore, a couple of individual rMal f allergens can improve the diagnosis of M. furfur-associated IgE allergies in patients with AD.

Association between oxidative stress and bone mineral density

Free radicals have been shown to be involved in bone resorption in vitro and in rodents. We studied the effect of oxidative stress on bone mineral density (BMD) in 48 women and 53 men from a population-based study. The levels of 8-iso-PGF(2alpha) (a major F(2)-isoprostane and a biomarker of oxidative stress) and a control, 15-keto-dihydro-PGF(2alpha) (a biomarker of inflammatory response), were measured in urinary samples and their association with BMD and quantitative ultrasound (QUS) measurements were examined. In multivariate linear regression analyses, 8-iso-PGF(2alpha) levels were negatively associated with both BMD and QUS. In contrast, no association was found for 15-keto-dihydro-PGF(2alpha). Our findings establish a biochemical link between increased oxidative stress and reduced bone density and provide a rational for further studies investigating the role of pro- and antioxidants in osteoporosis.

Vitamin A antagonizes calcium response to vitamin D in man

For unknown reasons, the highest incidence of osteoporosis is found in northern Europe. In these populations, the sunlight exposure is limited and the vitamin A intake is high. The interaction between vitamin A and D has been the subject of several in vitro and animal studies. We have studied the acute effects of vitamin A and D on calcium homeostasis in 9 healthy human subjects. We compared the effect of (i) 15 mg of retinyl palmitate, (ii) 2 microg of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], (iii) 15 mg of retinyl palmitate plus 2 microg of 1,25(OH)2D3, and (iv) placebo in a double-blind crossover study. The subjects took vitamin preparations at 10:00 p.m. and the following day blood samples were collected five times from 8:00 a.m. to 4:00 p.m. Serum levels of 1,25(OH)2D3 and retinyl esters increased (1.7-fold and 8.3-fold, respectively; p < 0.01). As expected, serum calcium (S-calcium) increased (2.3%; p < 0.01) and S-parathyroid hormone (PTH) decreased (-32%; p < 0.05) after 1,25(OH)2D3 intake. In contrast, retinyl palmitate intake resulted in a significant decrease in S-calcium when taken alone (-1.0%; p < 0.05) and diminished the calcium response to 1,25(OH)2D3 after the combined intake (1.4%; p < 0.01). S-PTH was unaffected by retinyl palmitate. No significant changes in serum levels of the degradation product of C-telopeptide of type I collagen (CrossLaps), or U-calcium/creatinine levels were found. In conclusion, an intake of vitamin A corresponding to about one serving of liver antagonizes the rapid intestinal calcium response to physiological levels of vitamin D in man.

Evidence for target-specific outgrowth from subpopulations of grafted human dopamine neurons

Clinical and experimental grafting in Parkinson's disease has shown the need for enhanced survival of dopamine neurons to obtain improved functional recovery. In addition, it has been suggested that a limited number of surviving dopamine neurons project to the dopamine-denervated host striatum. The aim of this study was to investigate if subpopulations of ventral mesencephalic dopamine neurons project to their normal targets, i.e., dorsal vs. ventral striatum. Following implantation of human ventral mesencepahlic tissue into the lateral ventricle of dopamine-depleted rats, human-derived dopamine reinnervation was achieved both in dorsal and ventral striatum. Treatment with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) resulted in a degeneration of tyrosine hydroxylase (TH)-immunoreactive nerve fibers in dorsal striatum but not in ventral areas in some animals, while MPTP was without effect in other animals. TH-immunoreactive neurons were small and appeared shrunken in animals carrying grafts affected by the MPTP treatment. In conclusion, grafted dopamine neurons projected nerve fibers into areas that they normally innervate. Thus, when searching for factors that may enhance survival of grafted dopamine neurons it is important to study which subpopulation(s) of ventral mesencephalic dopamine neurons is affected, such that a proper reinnervation may be achieved.

Prescription drug use, diagnoses, and healthcare utilization among the elderly

BACKGROUND

More elderly patients affected by severe and chronic diseases are treated in primary care. Reports on the use of prescription drugs by the general elderly population are scarce, and more investigations are needed to optimize pharmaceutical care for these patients.

OBJECTIVE

To analyze prescription drug use, diagnoses, and healthcare utilization among noninstitutionalized elderly patients.

DESIGN

Retrospective cohort study.

SETTING AND PATIENTS

All people > or =65 years old (n = 4642) living in the community of Tierp, Sweden, in 1994 were included. Prescription drug use and healthcare utilization have been registered for all inhabitants of the community since 1972. Information about filled prescriptions and diagnoses were obtained from a computerized research register.

RESULTS

Prescription drug use was high among the elderly (78%); the most used pharmacologic groups were cardiovascular, nervous system, and gastrointestinal medications. Women used more prescription drugs than men (average 4.8 vs. 3.8) and had more nonfatal diagnoses. Use of five or more different prescription drugs during 1994 was common (39.0%), and multivariate analysis showed that the greatest number of primary care visits occurred with multiple drug use (> or =5 drugs over 1 y).

CONCLUSIONS

This study shows an extensive multiple drug use among elderly people living at home. Whether this multiple drug use per se is harmful to the patients or not could not be evaluated in this study. Further focused investigations are needed to assess the effect of multiple drug use in an elderly population.

Giving advice on cost effective measures for a cleaner Baltic Sea: a challenge for science

The Baltic Sea is one of the world's seas that is most severely affected by human activities. Although there is an international agreement that nutrient input to the Baltic should be reduced, the measures taken so far have not resulted in major reductions in nutrient inputs nor in environmental improvements. The reasons for this are partly due to lack of knowledge on large-scale relationships and couplings between physics, biogeochemistry and ecological properties. But there is also a lack of overall drainage basin-wide analyses on cost-effective measures. There is a danger in making the wrong decisions, e.g. implement reduction schemes that are at worst ineffective or at best, far from cost effective. Researchers from many disciplines are faced with a common challenge: To develop a decision-support system, which can be used as the scientific base for cost-effective measures for the entire Baltic Sea. Such an effort is now being made within the research program MARE (http://www.mare.su.se).

Cytotoxicity of digitoxin and related cardiac glycosides in human tumor cells

The saponin digitonin, the aglycone digitoxigenin and five cardiac glycosides were evaluated for cytotoxicity using primary cultures of tumor cells from patients and a human cell line panel (representing different cytotoxic drug-resistance patterns). Of these seven compounds, proscillaridin A was the most potent (IC(50): 6.4--76 nM), followed by digitoxin, and then ouabain, digoxin, lanatoside C, digitoxigenin and digitonin. Correlation analysis of the log IC(50) values for the cell lines in the panel showed that compound cytotoxicity was only slightly influenced by resistance mechanisms that involved P-glycoprotein, topoisomerase II, multidrug resistance-associated protein and glutathione-mediated drug resistance. Digitoxin and digoxin expressed selective toxicity against solid tumor cells from patients, while proscillaridin A expressed no selective toxicity against either solid or hematological tumor cells. The results revealed marked differences in cytotoxicity between the cardiac glycosides, both in potency and selectivity, and modes of action for cytotoxicity that differ from that of commonly used anticancer drugs.

The functional role of a bicuculline-sensitive Ca2+-activated K+ current in rat medial preoptic neurons

A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent bicuculline methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of bicuculline methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, bicuculline methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by bicuculline methiodide.

Assembly of laminin polymers is dependent on beta1-integrins

Recent reports suggest that laminin deposition is controlled by the cell via specific receptors, one of which is dystroglycan. In this study, the involvement of beta1-integrins in this process was investigated by comparing beta1-integrin-deficient cells of different phenotypes with their normal counterparts. Normal embryonic stem (ES) cells and embryoid bodies (EBs) derived from them were found to deposit cell-associated laminin into fibrillar networks, and in the EBs a basement membrane was assembled under the primitive endoderm. beta1-deficient ES cells and their EBs formed only small amounts of dot-like laminin deposits. Skeletal myotubes formed after prolonged differentiation in EBs were found to be surrounded by laminin, nidogen, and perlecan by immunofluorescent staining irrespective of the presence of beta1-integrins on the myotubes. However, at the electron microscope level only very thin sheet-like structures were detected close to the beta1-deficient myotubes, while the wt myotubes formed thick basement membranes. An epithelial cell line, GE11, derived from the beta1-integrin-deficient ES cells was also unable to assemble laminin on the cell surface, while transfection of the cells with the integrin beta1 subunit resulted in formation of a dense laminin network. Taken together, these results suggest that dystroglycan and beta1-integrins can both contribute to the recruitment of laminin to cell surfaces and that integrins are required at a subsequent step in the formation of basement membranes.

Incidence of newly diagnosed heart failure in UK general practice

AIM

To estimate the incidence rate of heart failure in the general population and to assess risk factors associated with the occurrence of newly diagnosed heart failure.

METHODS

From the source population that was derived from the UK General Practice Research Database, we identified patients aged 40--84 years newly diagnosed with heart failure in 1996, and estimated incidence rates. We sent questionnaires to a random sample of heart failure patients (N=1200) and performed a nested case-control analysis to assess risk factors for heart failure.

RESULTS

The overall incidence rate for heart failure was 4.4 per 1000 person-years in men and 3.9 per 1000 person-years in women. The incidence increased steeply with age in both sexes. The relative risk of heart failure was 2.1 (95% C.I.: 1.7--2.6) among men compared with women less than 65 years old and 1.3 (95% C.I.: 1.2--1.4) above the age of 65. Slightly more than half of the cases were categorized in NYHA III--IV at the time of the first diagnosis. Within one month of initial diagnosis 62% of the men and 50% of the women were referred to specialists and/or hospitalized for heart failure. Smoking, hypertension, diabetes, obesity were independently associated with heart failure as well as history of distant dyspnoea. Coronary heart disease was the most common cause of heart failure with a greater relative prevalence in men than women.

CONCLUSION

Incident heart failure cases mainly comprised elderly men and women frequently burdened with several diseases in general practice. Women had a lower incidence of heart failure than men. However, traditional risk factors such as smoking, hypertension, obesity, diabetes and dyspnoea appeared to confer the same relative increase in heart failure risk among women and men.

Left sided vocal cord paralysis: a newly recognized late complication of mediastinal irradiation

BACKGROUND AND PURPOSE

To evaluate the incidence of vocal cord paralysis in a group of breast cancer patients treated with post operative radiation therapy after radical mastectomy.

MATERIALS AND METHODS

A group of 150 patients operated with total mastectomy and axillary clearance received, in 1963-1965, post-operative radiotherapy to the parasternal, axillary and supraclavicular lymph node regions. The cohort has now been followed up to 34 years.

RESULTS

Eleven of the 12 vocal cord paralyses were left sided, although the breast cancer was almost equally distributed as left- and right-sided (55 vs. 45%). The symptoms did not appear until 2-25 years after irradiation. Series 1 (treated with (60)Co photons) developed 5% recurrent nerve paralysis (RNP) after a median time of 19.0 years compared with 10% and a much earlier appearance (3.5 years) for series 2 (treated with both (60)Co photons and electrons). A reconstruction of the dose plan shows that an unintentional overlap of the fields resulted in hotspots in the tracheo-oesophageal groove, where parts of the tissue received 120-130% of the prescribed dose.

CONCLUSIONS

A left-sided vocal cord paralysis of patients treated with mediastinal radiotherapy might not indicate only tumour recurrence but also mediastinal fibrosis. Small differences in patient positioning cannot be excluded as the cause of the difference in the two series. We postulate that other more subtle damage to the vagus nerve may occur without being recognized as late radiation injury.

Lifetime measurements of metastable states in Fe+

The lifetime of two metastable levels in Fe+ has been measured by laser probing of a stored ion beam. In the dense spectrum of Fe+, the metastable levels a (6)S(5/2) and b (4)D(7/2) were selected and their lifetimes were determined to be 230 +/- 30 and 530 +/- 30 ms, respectively. The lifetimes are compared with previous theoretical results. Metastable lifetime measurements of Fe+ are of great importance for interpretation of spectra from astronomical objects. The present experiment opens for the possibilities to investigate lifetimes of metastable states in complex atomic ions, which have, so far, been unexplored.

Histologic grading in breast cancer--reproducibility between seven pathologic departments. South Sweden Breast Cancer Group

Histologic grade, including tubular formations, nuclear grade, and mitotic activity, is a well-documented prognostic factor in breast cancer. In comparison with other prognostic parameters, the evaluation of histologic grade is cheap and can be performed, in principle, in all cases of breast cancer. One possible disadvantage is that the evaluation may vary between different pathological departments. The aim of the present work was therefore to study the reproducibility of the histologic grading system by distributing haematoxylin-erythrosin-stained slides from 93 invasive breast cancers to the seven pathology departments within the southern healthcare region of Sweden. The evaluation was performed blindly and without any knowledge of other clinical parameters. In 31% of the cases the same histologic grade was obtained for all departments. The overall mean kappa was 0.54, indicating a moderate reproducibility. Of the three factors included in histologic grade, the agreement was best for tubular formations and poorest for nuclear grade and mitotic activity. The overall moderate reproducibility should be considered when the clinical usefulness of histologic grading is compared with other prognostic instruments.

Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae

One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium.