Specificity of loss of heterozygosity in radiation-induced mouse myeloid and lymphoid leukaemias

PURPOSE

To determine whether loss of heterozygosity (LOH) at specific chromosomal loci in radiation-induced leukaemias, arising in a similar genetic background, is leukaemia-type specific (myeloid versus lymphoid) or common to both.

MATERIALS AND METHODS

Leukaemias that arose in 3 Gy X-irradiated (CBA/H x C57BL/6)F1 intercross and backcross mice were diagnosed as acute myeloid leukaemia (AML) or thymic lymphoma (TL). LOH was determined using 28 polymorphic microsatellite markers distributed over seven chromosomes using control and leukaemic DNA from individual mice.

RESULTS

LOH incidences of 0-20% were observed at most loci in both leukaemia types. Specific LOH incidences of 38-76% were observed for myeloid (chromosome 2) and lymphoid (chromosomes 11 and 14) leukaemias. Chromosome 4 LOH was frequently (38-50%) observed in both types, although the commonly deleted regions differed. LOH was detected at either chromosome 2 or 4 in AML and either chromosome 4 or 11 in TL.

CONCLUSIONS

LOH incidences of 38-76% suggest a causal role of particular loci which is mainly, but not exclusively, dependent on leukaemia type. LOH incidences of 0-20% at other loci in both leukaemias suggest that many genetic deletions are non-causal and incidental in radiation-leukaemogenesis.

The natural history of exercise-induced anaphylaxis: survey results from a 10-year follow-up study

BACKGROUND

Exercise-induced anaphylaxis (EIA) is a unique physical allergy that is triggered by exertion, the clinical spectrum and modifying factors of which have been previously studied. At the time of initial description, it was postulated that other factors contributed to this disorder.

OBJECTIVE

We sought to determine the clinical course and potential modifying factors in EIA.

METHODS

In 1993, we conducted a cross-sectional analysis of 671 individuals with exercise-associated symptoms for more than a decade using a validated 75-item questionnaire. Subjects met criteria for EIA if they had anaphylactic symptoms, including hypotension or upper airway obstruction, urticaria, or angioedema with physical exertion but without a passive increase in core body temperature.

RESULTS

Of 365 (54%) questionnaire respondents, 279 (87%) met criteria for EIA (199 females and 80 males). At the time of study entry, subjects with EIA (mean age, 37.5 years; range, 13 to 77 years) had an average of 10.6 years of symptoms, which were most frequently triggered by aerobic activities such as jogging or brisk walking (78% and 42%, respectively). On average, subjects reported that the frequency of attacks had decreased (47% of subjects) or stabilized (46% of subjects) since onset. One hundred (41%) subjects reported being completely free of attacks in the past year. Subjects reduced their attacks by avoiding exercise during extremely hot or cold weather (44%), avoiding ingestion of certain foods before exercise (37%), and restricting exercise during their allergy season (36%) or humid weather (33%). The most common pharmacologic agents used to manage symptoms were H1 antagonists (56%) and/or epinephrine (31%). However, 28% used no treatment at all.

CONCLUSION

EIA is an episodic condition in which the frequency of attacks tends to stabilize or decrease over time. Improvement appears to result from individual modification of exercise and avoidance of known environmental and ingestible precipitants.

Monocyte chemotactic proteins in allergen-induced inflammation in the nasal mucosa: effect of topical corticosteroids

BACKGROUND

Human allergen-induced rhinitis is associated with the recruitment and activation of inflammatory cells, particularly eosinophils and CD4(+) T cells, in the nasal mucosa. Chemokines are inflammatory mediators capable of attracting specific inflammatory cell populations. Monocyte chemotactic proteins (MCPs), a subfamily of CC chemokines, have been shown to induce chemotactic activity particularly in eosinophils, T cells, and monocytes under in vitro assay conditions.

OBJECTIVE

To assess the contribution of MCPs in the recruitment of inflammatory cells in vivo, we investigated the allergen-induced late response in subjects with allergic rhinitis.

METHODS

Patients were randomized to receive a 6-week treatment with either topical corticosteroid (n = 6) or a matched placebo (n = 6). Nasal inferior turbinate biopsy specimens were obtained from all subjects before and during allergen-induced late responses. By using immunocytochemistry, tissue sections were examined for the presence of MCP-1, MCP-3, and MCP-4 and for the phenotype of infiltrating cells within the nasal mucosa. In addition, double sequential immunocytochemistry was used to confirm the phenotype of MCP-immunoreactive positive cells. Furthermore, the effect of topical corticosteroids on the expression of MCPs and on the cellular infiltrate was also examined.

RESULTS

MCP-1, MCP-3, and MCP-4 were expressed in all the baseline samples, with prominent staining observed within the nasal epithelium. Biopsy specimens taken after challenge exhibited significant upregulation in the expression of MCP-3 and MCP-4 (P <.001). On the other hand, this increase in response to allergen was reduced in patients pretreated with topical corticosteroids. Colocalization experiments revealed that the majority of MCP+ cells in the subepithelium were macrophages, followed by T cells and eosinophils.

CONCLUSION

Our results demonstrate that allergen-induced rhinitis is associated with an increased expression of MCP-3 and MCP-4, which may be closely related to the influx of inflammatory cells and may thus contribute to the pathogenesis of allergic rhinitis.

Hospital outcome measures following assertive community treatment in Edmonton, Alberta

OBJECTIVE

To examine hospital outcome measures for individuals with chronic and severe mental illnesses before and after their registration in an assertive community treatment (ACT) program in Edmonton, Alberta.

METHODS

Data were collected from Alberta Health on individuals who were registered in ACT from April 1993 to April 1995. For each individual, hospital outcome measures were calculated for the 365 days prior to and 365 days after registration for ACT (thus covering April 1, 1992-March 31, 1996).

RESULTS

Data were collected from 295 individuals. Compared with 1 year prior to beginning ACT, there was a 34% reduction in hospital separations for patients with psychiatric diagnoses. The average length of stay (LOS) for each separated patient decreased by 56%, and the hospitalization days for each patient separated also decreased by 39%. The number of emergency visits for psychiatric reasons was reduced by 32%, and the number of clients visiting emergency departments for psychiatric reasons declined by 30%.

CONCLUSIONS

In the 1-year period after registration in an ACT program, hospital outcome measures were improved in this cohort of 295 individuals with severe and chronic mental illnesses.

Power dependence of dynamic spatial replenishment of femtosecond pulses propagating in air

Numerical simulations of nonlinear pulse propagation in air show an initial pulse formed, absorbed by plasma generation, and subsequently replenished by power from the trailing edge. Here we show that this scenario implies that the length scale for filament propagation is relatively insensitive to the peak input power beyond the threshold for filament generation.

Sustained induction of fetal hemoglobin by pulse butyrate therapy in sickle cell disease

High levels of fetal hemoglobin (Hb F) protect from many of the complications of sickle cell disease and lead to improved survival. Butyrate and other short chain fatty acids were previously shown to increase Hb F production in erythroid cells in vitro and in animal models in vivo. However, butyrates are also known to inhibit the proliferation of many cell types, including erythroid cells. Experience with the use of butyrate in animal models and in early clinical trials demonstrated that the Hb F response may be lost after prolonged administration of high doses of butyrate. We hypothesized that this loss of response may be a result of the antiproliferative effects of butyrate. We designed a regimen consisting of intermittent or pulse therapy in which butyrate was administered for 4 days followed by 10 to 24 days with no drug exposure. This pulse regimen induced fetal globin gene expression in 9 of 11 patients. The mean Hb F in this group increased from 7.2% to 21.0% (P <.002) after intermittent butyrate therapy for a mean duration of 29.9 weeks. This was associated with a parallel increase in the number of F cells and F reticulocytes. The total hemoglobin levels also increased from a mean of 7.8 g/dL to a mean of 8.8 g/dL (P <.006). The increased levels of Hb F were sustained in all responders, including 1 patient who has been on pulse butyrate therapy for more than 28 months. This regimen, which resulted in a marked and sustained increase in Hb F levels in more than two thirds of the adult sickle cell patients enrolled in this study, was well tolerated without adverse side effects. These encouraging results require confirmation along with an appropriate evaluation of clinical outcomes in a larger number of patients with sickle cell disease.

The significance of choroid plexus cysts in an unselected population: results of a multicenter study

OBJECTIVES

Choroid plexus cysts are commonly found at the time of a routine second-trimester scan, but there is much debate as to their clinical significance. The aims of this study were to define the incidence of choroid plexus cysts in an unselected population and describe their association with aneuploidy.

DESIGN

This was a prospective, observational multicenter study.

SUBJECTS

Subjects were all fetuses found to have choroid plexus cysts with a maximum diameter of 3 mm or greater and who were between 14 and 24 weeks' gestation when scanned in the routine ultrasound department at any of the 13 participating hospitals.

RESULTS

There were 658 fetuses with choroid plexus cysts in a total of 101,600 births. The overall incidence of aneuploidy was 2.1%, but in fetuses with isolated choroid plexus cysts the incidence of proven aneuploidy was 0.5% (95% confidence interval (CI), 0.1-1.4%). If age is taken into consideration, then the incidence of aneuploidy in fetuses with isolated choroid plexus cysts where the mother is under the age of 36 years was 0.36% (95% CI, 0.04-1.3%), and 2.4% (95% CI, 0.06-12.6%) in older women.

CONCLUSIONS

We conclude that the presence of choroid plexus cysts increases the risk for aneuploidy, mainly trisomy 18. In the majority of cases, the final risk will remain small, but will increase as maternal age increases.

Genetic instability in radiation-induced leukaemias: mouse models

PURPOSE

Genetic instability plays a major role in multi-stage carcinogenesis. Ionizing radiation induces delayed genetic instability which can be transmitted to the clonal offspring of the irradiated cell, so it is of considerable importance to determine whether radiation-induced genetic instability contributes to radiation-leukaemogenesis.

RESULTS

The experimental data obtained using radiation-induced leukaemias in mouse models were reviewed, and an attempt was made to distinguish between the instability detectable in de novo cancers and that which is associated with ionising radiation. Genetic lesions identified in mouse leukaemias include non-clonal chromosomal aberrations, loss of heterozygosity, and minisatellite/microsatellite mutations.

CONCLUSIONS

Studies of mouse radiation-induced leukaemias have detected evidence of genetic instability. However, with few exceptions, most of this instability was also observed during de novo multi-stage carcinogenesis. This raises the possibility that radiation induces ongoing genetic instability that is functionally indistinguishable to that implicated in de novo tumour progression.

Expression of IgE heavy chain transcripts in the sinus mucosa of atopic and nonatopic patients with chronic sinusitis

We have recently shown the increased mRNA expression of interleukin (IL)-4 and IL-13 in sinus biopsies from allergic subjects with chronic sinusitis (ACS), whereas only IL-13 mRNA was elevated in biopsies obtained from nonallergic subjects with chronic sinusitis (NCS). In the lymph nodes and spleen, these cytokines may promote IgE production through transcriptional activation of the germline IgE heavy chain promoter, an event which precedes immunoglobulin isotype switching to IgE in B cells. We hypothesized that local expression of IL-4 and/or IL-13 might act by inducing germline IgE heavy chain transcript expression locally in the sinus mucosa of chronic sinusitis patients. Mucosal sinus biopsies were obtained from 13 patients with ACS, 12 subjects with NCS, and 11 normal control individuals. The numbers of B cells in the sinus mucosa were studied by immunocytochemistry with anti-CD20 monoclonal antibodies. In situ hybridization was performed using antisense radiolabeled riboprobes complementary to the IgE epsilon -heavy chain germline (Iepsilon) and heavy chain constant region (Cepsilon) gene transcripts. Riboprobes specific for the IgG gamma-heavy chain constant region (Cgamma) were used as an isotype control. Immunocytochemical analysis indicated augmented numbers of CD20-positive B cells in the biopsies obtained from ACS patients compared with NCS subjects (P < 0.05) and normal control subjects (P < 0.01). Statistically significant increases were observed in the numbers of cells expressing Iepsilon and Cepsilon transcripts in the sinus mucosa of ACS patients compared with those with NCS (P < 0. 001) and normal controls (P < 0.001), while Cgamma RNA expression did not differ significantly between the groups. In three randomly selected ACS biopsies, 92-100% of cells expressing Cepsilon transcripts and 100% of Iepsilon RNA-positive cells coexpressed CD20 immunoreactivity. Cells expressing Cepsilon transcripts were also significantly increased in NCS compared with normal controls (P < 0. 05). The results of this study suggest that local IgE class switching occurs in the pathogenesis of ACS and that ACS and NCS are both associated with increased expression of Cepsilon transcripts.

Pulse shapes and stability in Kerr and Active Mode-Locking (KAML)

We present numerical simulations of laser mode-locking using a spatio-temporal master equation. We look at active mode-locking using an amplitude modulator and compare the results with those found using a phase modulator. We find gaussian pulses and stability conditions consistent with the Kuizenga-Siegman theory of mode-locking. We then add a Kerr medium to the cavity and examine the effect this has on the mode-locking process, the stability, and the shape of the final pulses. We find that the pulses are significantly compressed in both space and time, and the profiles become more sech-like.

Stroke prevention trial in sickle cell anemia

Stroke occurs in 7-8% of children with Sickle Cell Disease (Hb SS) and is a major cause of morbidity. Rates of recurrence have been reduced from 46-90% to less than 10% through chronic blood transfusions. Prevention of first stroke, however, would be preferable because even one stroke can cause irreversible brain injury. Transcranial Doppler (TCD) ultrasound can detect arterial blood flow rates associated with subsequent stroke risk. By combining TCD screening and a potentially effective treatment, first stroke may be prevented. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) is the first stroke prevention trial in Hb SS and the first randomized, controlled use of transfusion in Hb SS. This multi-center trial is designed to test whether reducing sickle hemoglobin to 30% or less with periodic blood transfusions will reduce first-time stroke by at least 70% compared to standard care. Primary endpoints will be clinically evident symptoms of cerebral infarction with consistent findings on Magnetic Resonance Imaging and Angiography (MRI/MRA) or symptomatic intracranial hemorrhage. Secondary endpoints will be asymptomatic brain lesions detected by MRI in brain areas not involved in primary endpoints. The design calls for a 6-month start-up interval, 18 months of TCD screening and randomization, and observation for stroke from entry through month 54. Key features of the trial are standardized TCD and MRI/MRA protocols interpreted blindly, and blinded adjudication of endpoints. The sample size (60 per treatment group) is based on prospective data relating TCD velocity to risk of stroke. A time-averaged mean velocity of > or = 200 cm/sec is associated with a 46% risk of cerebral infarction over 39 months. The sample size is sufficient to detect 70% reduction in the primary endpoint at 90% power. This trial will determine if transfusion is effective in the primary prevention of stroke. Secondary aims may further the understanding of the effects of transfusion on the brain and guide future research into cerebrovascular disease in Hb SS.

A randomised prospective comparison of operative peripheral iridectomy and Nd:YAG laser iridotomy treatment of acute angle closure glaucoma: 3 year visual acuity and intraocular pressure control outcome

AIM

To compare visual acuity and intraocular pressure outcomes 3 years after treatment of acute angle closure glaucoma (AACG) by operative peripheral iridectomy (PI) or Nd:YAG laser iridotomy (YAG PI).

METHODS

A prospective study of consecutive patients presenting to one ophthalmology department with uniocular AACG during a 2 year period. Following informed consent patients were randomised to bilateral PI or bilateral YAG PI. Three years after treatment the mean Snellen visual acuity converted to logMAR scores of the two groups was compared using the unpaired Student's t test. The number of patients with normal intraocular pressure with no further treatment in each group was compared using the chi 2 test with Yates's correction.

RESULTS

21 patients underwent bilateral PI and 27 bilateral YAG PI. Three years after treatment visual acuity was 0.30 (SD 0.28) log MAR units for PI eyes and 0.57 (0.67) logMAR units for YAG PI eyes (p = 0.08, NS). 15 (70.4%) PI eyes and 19 (71.8%) YAG PI eyes had an intraocular pressure less than 21 mm Hg with no further treatment (NS).

CONCLUSIONS

There was no significant difference in visual acuity or intraocular pressure control 3 years after treatment of AACG with PI or YAG PI.

Expression of the Sox11 gene in mouse embryos suggests roles in neuronal maturation and epithelio-mesenchymal induction

Sry, the mammalian Y-linked testis determining gene, is a member of a family of genes known as Sox genes, which encode transcription factors related by a DNA-binding motif termed the HMG box. Sox genes are known to have diverse roles in vertebrate differentiation and development. We report here the cloning and characterisation of one of these genes, Sox11, in mice. In addition to an N-terminal HMG box domain, the deduced SOX11 protein contains a number of highly conserved C-terminal motifs, which may function in transcriptional regulation. Expression of Sox11 in mouse embryos was prominent in the periventricular cells of the central nervous system, suggesting a role in neuronal maturation. Expression was also observed in a wide range of tissues involved in epithelial-mesenchymal interactions, suggesting an additional role in tissue modelling during development.

A controlled trial of an educational program to prevent low back injuries

BACKGROUND

Low back injuries are common and costly, accounting for 15 to 25 percent of injuries covered by workers' compensation and 30 to 40 percent of the payments made under that program. The high costs of injury, the lack of effective treatment. and the evidence that there are behavioral risk factors have led to widespread use of employee education programs that teach safe lifting and handling. The effectiveness of those programs, however, has received little rigorous evaluation.

METHODS

We evaluated an educational program designed to prevent low back injury in a randomized, controlled trial involving about 4000 postal workers. The program, similar to that in wide use in so-called back schools, was taught by experienced physical therapists. Work units of workers and supervisors were trained in a two-session back school (three hours of training), followed by three to four reinforcement sessions over the succeeding few years. Injured subjects (from both the intervention and the control groups) were randomized a second time to receive either training or no training after their return to work.

RESULTS

Physical therapists trained 2534 postal workers and 134 supervisors. Over 5.5 years of follow-up, 360 workers reported low back injuries, for a rate of 21.2 injuries per 1000 worker-years of risk. The median time off from work per injury was 14 days (range, 0 to 1717); the median cost was $204 (range, zero to $190,380). After their return to work, 75 workers were injured again. Our comparison of the intervention and control groups found that the education program did not reduce the rate of low back injury, the median cost per injury, the time off from work per injury, the rate of related musculoskeletal injuries, or the rate of repeated injury after return to work; only the subjects' knowledge of safe behavior was increased by the training.

CONCLUSIONS

A large-scale, randomized, controlled trial of an educational program to prevent work-associated low back injury found no long-term benefits associated with training.

Ongoing Y-chromosome instability defines sub-clonal variants in radiation-induced leukaemias in the mouse

Forty primary leukaemias that arose in vivo as a consequence of 3 Gy X-irradiation of inbred mouse strains were analysed for Y-chromosome aberrations by conventional cytogenetics and fluorescent in situ hybridization (FISH). Compared with control mice which were X-irradiated but which exhibited no overt signs of leukaemia, the loss and gain of Y-chromosomes in leukaemic spleen cells defined subclonal variants in the radiation-induced haemopoietic malignancies that arose in CBA/H, DBA/2 and (C57BL/6 x DBA/2)F1 mice. This Y-chromosome instability was significantly higher than that observed in spleen cells of age-matched (or older) irradiated control mice that had not developed overt leukaemia. The detection of Y-chromosome aberrations is considered in the context of the high numbers of potential gene regulatory sequences in the murine Y-chromosome and the potential for the insertional activation of cellular genes during multi-stage radiation leukaemogenesis.

Mini- and microsatellite mutations in radiation-induced acute myeloid leukaemia in the CBA/H mouse

Radiation-induced acute myeloid leukaemia (AML) in the CBA/H mouse is a clonal disorder and therefore amenable to the analysis of genetic instability during radiation leukaemogenesis. The genotype of a single minisatellite and 20 microsatellite loci was compared in tail and leukaemic spleen DNA prepared from the same mouse. Somatic mutation at the Ms6-hm minisatellite locus was nearly seven times higher (27%, 4/15) than the spontaneous germline mutation rate (4%). Only 1/15 AMLs exhibited microsatellite mutations, but 5/20 loci were mutated in the same AML, indicating that it was deficient in mismatch repair. Thus, whereas somatic minisatellite mutations, which are associated with complex intra-allelic gene conversion events, occur at a very high rate in the radiation-induced AMLs, microsatellite instability, which has been associated with the acquisition of the replication error repair (RER+) phenotype, is infrequent but detectable.