Recombination between separate MYC amplification structures in COLO320 cells

Cytogenetically visible gene amplification structures can consist of arrays of amplicons presumably formed by secondary “rearrangements” following amplicon formation. The structural evolution of gene amplification sites in tumor cells suggests that complex secondary structures may have some selective advantage in the tumor cell environment. Although secondary amplicon rearrangements are a hallmark of the gene amplification process, little is known about the mechanics of this process. COLO320 neuroendocrine tumor cells carry two different types of amplified MYC oncogene sequences, one type with an intact MYC gene and the other with a rearranged “chimeric” MYC gene. We have studied various clonal subpopulations of COLO320 cells and identified regions within and downstream of the MYC locus that are unique to each amplicon type. Using double-label fluorescence in situ hybridization with DNA probes unique to each amplicon type, we have observed that both chromosomal and extrachromosomal MYC amplicon arrays in COLO320 cells frequently consist of heterogeneous mixtures of each MYC amplicon type. Our results suggest that the two MYC amplicon types of COLO320 cells were formed simultaneously but independently, and that double minute chromosomes observed in COLO320 cells were formed by intermolecular homologous recombination secondary to amplicon formation. © 1993 Wiley-Liss, Inc.     

Electrophoretic isolation of extrachromosomal DNA from tumor cells

Gene amplification allows transformed cells to overexpress specific genes and gain a survival advantage. For this reason, cloning and characterization of amplified genes can improve our understanding of the biology of transformed cells. The techniques of in-gel renaturation and chromosome microdissection can enrich for amplified DNA sequences, but both are labor intensive and have other drawbacks. We have developed an alternative strategy of enriching for amplified DNA sequences that involves two-directional agarose gel electrophoresis of extrachromosomal circular DNA. Extrachromosomal circles can be detected with repetitive DNA probes and can be used to produce DNA probes suitable for fluorescence in situ hybridization for location of genomic origin. The ability to enrich for amplified DNA without specialized equipment or transformed cell metaphases should prove useful in the search for new genes which are important in tumor cell progression.     

Plasma level distribution, effect and toxicity of antiepileptic drugs among Ethiopian epileptics

Plasma phenytoin and phenobarbitone levels were estimated in 123 adult Ethiopian epileptics by gas-liquid chromatography. Thirty four (38.2%) of the patients on phenytoin, and 52 (52%) of those on phenobarbitone, had plasma levels in the conventional therapeutic ranges of 10-20 micrograms/ml and 10-30 micrograms/ml respectively. Of the 89 patients who were taking phenytoin either singly or combined with phenobarbitone, motor disturbances (ataxia and nystagmus) were seen in 31 (34.8%) and dysmorphic and idiosyncratic side effects including gum hypertrophy, hirsutism, acne and skin rash in 37 (41.6%). Subnormal serum calcium levels were noted in 15 (30.6%) and high alkaline phosphatase was found in 13 (26.5%). Phenobarbitone was found to be an effective anticonvulsant (78.1% seizure control rate), with adverse effects of sedation and intellectual depression. Seizure control was achieved in 77.1% of patients on a single drug as opposed to 55.6% on combination of phenytoin and phenobarbitone (p less than 0.05). The overall seizure control rate was 66%.     

Field efficacy of praziquantel oral paste against naturally acquired equine cestodes in Ethiopia

The efficacy of an oral formulation of praziquantel (Equitape, Horse paste, Fort Dodge) in the reduction of cestode egg counts and serum antibody level against Anoplocephala perfoliata was assessed in 44 donkeys under field conditions. The donkeys were confirmed both by faecal examination and serum antibody assessed by an enzyme-linked immunosorbent assay to have natural infection with tapeworms. The donkeys were randomly allocated into treatment (n?=?22) and control (n?=?22) groups. The treatment group was treated with both praziquantel and ivermectin (Ivomec, Merial) at a dose rate of 1 mg/kg and 200 μg/kg, respectively while the control group was treated only with ivermectin. Faecal samples were collected before treatment (day-0) and 2, 6, 8, 12, and 16 weeks post-treatment while blood samples were collected before treatment and 8 and 16 weeks after treatment and analysed. The results of the study demonstrated that praziquantel paste was highly effective in reducing cestode eggs in donkeys and had an efficacy of more than 99 % until week 16 (day?112). No cestode egg reappearance by 16 weeks post-treatment in any animal in the treatment group was observed while donkeys in the control group continued shedding cestode eggs. The immunological assay also showed a significant reduction in serum antibody level against A. perfoliata in treated donkeys compared to the control group (p?=?0.0001). This marked decrease in serum antibody level indicates reduced risk of cestode-associated colic and other gastrointestinal disorders and clinical diseases. No adverse reactions or clinical effects were encountered in any animal within either group throughout the trial period.     

Prevalence of Disability and Associated Factors among Registered Leprosy Patients in All Africa Tb and Leprosy Rehabilitation and Training Centre (ALERT), Addis Ababa,Ethiopia

Background

Delay in leprosy diagnosis and treatment causes disabilities due to nerve damage, immunological reactions and bacillary infiltration. Leprosy disability leads not only to physical dysfunction and activity limitation but also disrupts social interaction of affected individuals by creating stigma and discrimination. This study was aimed at assessing leprosy disability status in patients registered at All African TB and Leprosy Rehabilitation and Training Centre.

Methods

Medical records of leprosy patients registered from September 11, 2010 to September 10, 2013 G.C were reviewed. Prevalence of disability calculated, bivariate and multiple logistic regressions were used to determine crude and adjusted odds ratios with 95% confidence interval.

Results

The overall prevalence of disability was found to be 65.9% from all categories of patients (40.2% Grade I and 25.7% Grade II). The Prevalence among the new category was 62.8% (39.1% Grade 1 and 23.7% Grade 2). Those ageed above 30 years, with duration of symptoms 6–12 months and above 24 months, with sensory loss, nerve damage and reversal reaction were more likely to develop disability.

Conclusion

In this study the prevalence of disability, both Grade I and II, is very high. Disability was associated with age, duration of symptom, sensory loss, signs of nerve damage and reversal reaction. These risk factors indicate the existence of delay in diagnosis and treatment of leprosy cases. Therefore, the national leprosy control program should investigate leprosy case detection and diagnosis system in the country and work on improving early case detection and prevention of disability.