Extreme altitude mountaineering and Type 1 diabetes; the Diabetes Federation of Ireland Kilimanjaro Expedition

AIMS

To examine the effects of extreme altitude mountaineering on glycaemic control in Type 1 diabetes, and to establish whether diabetes predisposes to acute mountain sickness (AMS).

METHODS

Fifteen people with Type 1 diabetes and 22 nondiabetic controls were studied during the Diabetes Federation of Ireland Expedition to Kilimanjaro. Daily insulin requirements, blood glucose estimations and hypoglycaemic attacks were recorded in diaries by the people with diabetes. The performance of blood glucose meters at altitude was assessed using standard glucose solutions. Symptoms of acute mountain sickness were recorded daily by people with diabetes and by the nondiabetic controls using the Lake Louise Scoring Charts. The expedition medical team recorded the incidence of complications of altitude and of diabetes. The final height attained for each individual was recorded by the expedition medical team and verified by the expedition guides.

RESULTS

The final altitude ascended was lower in the diabetic than the nondiabetic group (5187 +/- 514 vs. 5654 +/- 307 m, P = 0.001). The mean daily insulin dose was reduced from 67.1 +/- 28.3-32.9 +/- 11.8 units (P < 0.001), but only 50% of recorded blood glucose readings were within the target range of 6-14 mmol/L. There were few hypoglycaemic attacks after the first two days of climbing. Both blood glucose meters tested showed readings as low as 60% of standard glucose concentrations at high altitude and low temperatures. The Lake Louise questionnaires showed that symptoms of AMS occurred equally in the diabetic and nondiabetic groups. There were two episodes of mild diabetic ketoacidosis; two of the diabetic group and three of the nondiabetic group developed retinal haemorrhages.

CONCLUSIONS

People with Type 1 diabetes can participate in extreme altitude mountaineering. However, there are significant risks associated with this activity, including hypoglycaemia, ketoacidosis and retinal haemorrhage, with the additional difficulties in assessing glycaemic control due to meter inaccuracy at high altitude. People with Type 1 diabetes must be carefully counselled before attempting extreme altitude mountaineering.

Acute onset of obsessive-compulsive disorder in males following childbirth

Research on postpartum onset obsessive-compulsive disorder (OCD) has focused exclusively on females. However, the authors present four cases of males with OCD onset that coincide with a spouse's pregnancy or delivery. The rapid onset and content of obsessions and compulsions are remarkably similar to those reported in previous studies of postpartum OCD in females. Each patient also responded to cognitive-behavioral therapy using exposure procedures. The implications of these cases for etiological models of postpartum OCD and future research directions are discussed.

Formation of nanomolar concentrations of S-nitroso-albumin in human plasma by nitric oxide

S-Nitrosothiols are potentially important mediators of biological processes including vascular function, apoptosis, and thrombosis. Recent studies indicate that the concentrations of S-nitrosothiols in the plasma from healthy individuals are lower than previously reported and in the range of 30-120 nM. The mechanisms of formation and metabolism of these low nM concentrations, capable of exerting biological effects, remain unknown. An important issue that remains unresolved is the significance of the reactions of low fluxes of nitric oxide (NO) with oxygen to form S-nitrosothiols in a complex biological medium such as plasma, and the impact of red blood cells on the formation of S-nitrosothiols in blood. These issues were addressed by exposing plasma to varying fluxes of NO and measuring the net formation of S-nitrosothiols. In the presence of oxygen and physiological fluxes of NO, the predominant S-nitrosothiol formed is S-nitroso-albumin at concentrations in the high nM range (approximately 400-1000 nM). Although the formation of S-nitrosothiols by NO was attenuated in whole blood, presumably by erythrocytic hemoglobin, significant amounts of S-nitrosothiols within the physiological range of S-nitrosothiol concentrations (approximately 80 nM) were still formed at physiological fluxes of NO. Little is known about the stability of S-nitroso-albumin in plasma, and this is central to our understanding of the biological effectiveness of S-nitrosothiols. Low molecular weight thiols decreased the half-life of S-nitroso-albumin in plasma, and the stability of S-nitroso-albumin is enhanced by the alkylation of free thiols. Our data suggests that physiologically relevant concentrations of S-nitrosothiols can be formed in blood through the reaction of NO with oxygen and proteins, despite the low rates of reaction of oxygen with NO and the presence of erythrocytes.

Clearance of the cervical spine in multitrauma patients: the role of advanced imaging

The cervical spine is injured in 3% of major trauma patients. Radiographic clearance for injury must be provided efficiently and accurately. There are numerous choices for clearance that are now in clinical practice: lateral radiograph only, 3-view or 5-view cervical-spine (c-spine) series, flexion-extension radiographs, computed tomography (CT) with multiplanar reformations, and magnetic resonance imaging (MRI). This article reviews the literature on methods of c-spine clearance, and emphasizes the pitfalls of each modality. Although lateral radiographs detect 60% to 80% of c-spine fractures, a significant number of fractures are not visible, even when three views of the spine are obtained. The sensitivity of plain radiographs can be improved by attention to several subtle features, which are discussed. Flexion-extension radiographs in the acute setting have an unacceptably high false-negative and false-positive rate. CT detects 97% to 100% of fractures, but its accuracy in detection of purely ligamentous injuries has not been documented. Furthermore, CT is limited in patients with severe degenerative disease. MRI is highly sensitive in the detection of ligamentous injury, but not all cases of injury may cause instability. MRI is also much less sensitive than CT to fractures of the posterior elements of the spine, and to injuries of the craniocervical junction. The causes of missed cervical spine injury and delayed instability are discussed and shown in this article. An algorithm for the use of advanced imaging is proposed.

On-wafer spectrofluorometric method for determination of relative quantum yields of photoacid generation in chemically amplified resists

Chemically amplified resists (CARs) that employ acid catalysts are widely used throughout the semiconductor industry due to the need for high throughput in the lithography process. The quantum yield of the particular photoacid generator (PAG) used to generate a given acid ultimately limits the photospeed of the CAR. Determination of quantum yields of photoacid generation is therefore an important component of resist design. We report the development of an on-wafer spectrofluorometric technique for this purpose. This technique is based on one first reported by Feke et al. (J. Vac. Sci. Technol. 2000, B18, 136- 139), which involves doping the resist formulations containing the candidate PAGs with a fluorescent pH indicator dye, coating one wafer per PAG, patterning the wafers with a dose ramp, and spectroscopically imaging the wafers. The response curve of each PAG is spatially and spectrally encoded in the fluorescence images of each wafer. We investigate the efficacy of coumarin 6, a dye that was introduced as an acid sensor by Pohlers et al. (Chem. Mater. 1997, 9, 3222-3230) for this application. We further apply this technique to the determination of the quantum yield of photoacid generation of four candidate PAGs for prototype 193-nm CARs. This technique is convenient, fast, robust, and nondestructive.

Results of salvage cryoablation of the prostate after radiation: identifying predictors of treatment failure and complications

PURPOSE

We conduct a critical evaluation of cryoablation of prostate cancer after failure of full dose radiotherapy to identify predictors of treatment failure and complications.

MATERIALS AND METHODS

A total of 125 cryoablation procedures were performed in 118 patients with proved local recurrence after full dose radiotherapy. Followup includes serial prostate specific antigen (PSA) and biopsy at 6,12 and 24 months. Kaplan-Meier plots were constructed for different PSA cutoffs. We separately analyzed different cohorts based on T stage, Gleason score, PSA before cryoablation and endocrine therapy status.

RESULTS

Of the 118 patients 114 had serum PSA nadir less than 0.5 ng./ml. Median followup was 18.6 months (range 3 to 54). Of the biopsy cores 3.1% (23 of 745) from 7 patients contained persistent viable cancer. Kaplan-Meier plots showed patients free of histological failure leveling at 87% and free from biochemical failure at 68%, 55% and 34%, respectively, with PSA greater than 4, 2 and 0.5 ng./ml. PSA greater than 10 ng./ml. before cryoablation, Gleason score 8 or greater before radiation and stage T3/T4 disease appeared to predict an unfavorable biochemical outcome. Serious complications included 4 rectourethral fistulas (3.3%) and severe incontinence (6.7%). Strong predictors of complications included bulky disease for fistulas and prior transurethral surgery.

CONCLUSIONS

Salvage cryoablation after radiation can achieve reasonable biochemical and histological results with acceptable morbidity. Cryoablation appears to be a reasonable treatment option for this patient population with few viable therapeutic options, provided vigorous patient selection criteria are adhered to.

Establishing surveillance for diabetes in American Indian youth

OBJECTIVE

To determine prevalence estimates in order to monitor diabetes, particularly type 2 diabetes, in American Indian youth.

RESEARCH DESIGN AND METHODS

To explore the feasibility of developing a case definition using information from primary care records, all youth aged <20 years with an outpatient visit or hospitalization for diabetes were identified from the Billings Area Indian Health Service database in Montana and Wyoming from 1997 to 1999, and the medical records were reviewed. Classification for probable type 1 diabetes was based on age < or =5 years, weight per age < or =15th percentile at diagnosis, or positive results of islet cell antibody test. Classification for probable type 2 diabetes was based on weight per age > or =85th percentile or presence of acanthosis nigricans at diagnosis, elevated C-peptide or insulin, family history for type 2 diabetes, or use of oral hypoglycemic agents with or without insulin or absence of current treatment 1 year after diagnosis.

RESULTS

A total of 52 case subjects with diabetes were identified, 3 of whom had diabetes secondary to other conditions. Of the remaining 49 case subjects, 25 (51%) were categorized as having probable type 2 diabetes, 14 (29%) as having probable type 1 diabetes, and 10 (20%) could not be categorized because of missing or negative information. Prevalence estimates for diabetes of all types, type 1 diabetes, and type 2 diabetes were 2.3, 0.6, and 1.1, respectively, per 1,000 youth aged <20 years.

CONCLUSIONS

Our definitions may be useful for surveillance in primary care settings until further studies develop feasible case definitions for monitoring trends in diabetes among youth.

Nitric oxide and the liver

In recent years, the role of nitric oxide (NO) in the pathogenesis of liver disease and its complications has been extensively studied. There remain, however, many areas of controversy. In particular, the effect of NO on vascular function in the systemic circulation and the hepatic microcirculation has received the greatest attention. It has been proposed on the one hand that increased NO synthesis is responsible for the development of the hyperdynamic circulation in cirrhosis, while decreased production of NO within the hepatic microcirculation may be important in the development of parenchymal tissue damage and the onset of portal hypertension. The purpose of this review is to examine the available data concerning the role of NO in liver disease and to discuss some of the controversies and contradictions that surround it.

Cardiovascular disease and risk factors in Montana American Indians and non-Indians

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death for both American Indian and non-Indian adults. Few published studies have compared the prevalence of CVD and related risk factors in Indians to that in non-Indians in the same geographic area.

OBJECTIVE

To compare CVD and risk factors in American Indian and non-Indian populations in Montana.

METHODS

Adult American Indians (n=1000) living on or near Montana's seven reservations and non-Indian (n=905) Montanans statewide were interviewed through the 1999 Behavioral Risk Factor Surveillance Survey (BRFSS).

RESULTS

Indians aged > or =45 years reported a significantly higher prevalence of CVD compared to non-Indians (18% vs 10%). In persons aged 18-44 years, Indians were more likely to report hypertension (15% vs 10%), obesity (29% vs 12%), and smoking (42% vs 24%) compared to non-Indians. For persons aged > or =45 years, Indians reported higher rates of diabetes (24% vs 9%), obesity (38% vs 16%), and smoking (32% vs 13%) compared to non-Indians. Non-Indians aged > or =45 years reported having been diagnosed with high cholesterol more frequently than did Indians (32% vs 24%).

CONCLUSIONS

Both Indians and non-Indians in Montana reported a substantial burden of CVD. The CVD risk patterns differ in the two populations. Prevention programs should be tailored to the risk burdens in these communities with particular emphasis on smoking cessation and the prevention of obesity.

Subtelomeric sequence from the right arm of Schizosaccharomyces pombe chromosome I contains seven permease genes

The sequence has been determined of 80 888 bp of contiguous subtelomeric DNA, including the isp5 gene, from the right arm of chromosome I of Schizosaccharomyces pombe; 27 open reading frames (ORFs) longer than 100 codons are present, giving a density of one gene per 3.0 kb. Seven of the predicted proteins are members of the major facilitator superfamily (MFS) of transport proteins, including four amino acid permease homologues, bringing this family of amino acid permease sequences to 17 in Sz. pombe, and a phylogenetic analysis is presented. Also encoded is an allantoate permease homologue, a sulphate permease homologue and a probable urea active transporter. Predicted non-membrane proteins include a 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase), a class III aminotransferase, serine acetyltransferase, protein-L-isoaspartate O-methyltransferase, alpha-glucosidase, alpha-galactosidase, esterase/lipase, oxidoreductase of the short-chain dehydrogenase/reductase (SDR) family, aldehyde dehydrogenase, formamidase, amidase, flavohaemoprotein, a putative translation initiation inhibitor and a protein with similarity to a filamentous fungal conidiation-specific protein. The remaining six ORFs are likely to encode proteins, either because they have sequence similarity with hypothetical proteins or because they are known to be transcribed. Introns are scarce in the sequenced region: only three ORFs contain introns, with only one having multiple introns. The sequenced region also contains a single Tf1 transposon long terminal repeat (LTR). The sequence is derived from cosmid clones c869, c922 and c1039 and has been submitted to the EMBL database under entries SPAC869 (Accession No. AL132779), SPAC922 (AL133522) and SPAC1039 (AL133521).

Causes and effects of the chronic inflammation in venous leg ulcers

The pathogenesis of venous leg ulcers is multifactorial. In this review article new physiological, molecular and cellular abnormalities in venous ulcers related to the chronic inflammation are presented and discussed. Venous hypertension causes disturbed microcirculation and pathological changes of the capillaries, which eventually locks the condition in a self-amplifying, detrimental cascade with persistent elevated levels and activities of pro-inflammatory cytokines and proteases preventing progress into a healing phase. As a consequence fibroblasts senescence and become less responsive to growth factors the older the ulcers become. Current data imply there is no deficiency but rather an unfavorable distribution of growth factors in venous ulcers. An imbalance in proteolytic enzymes and their endogenous inhibitors is a common finding in chronic venous leg ulcers. Variation in disease severity and concomitant ailments in this heterogeneous patient group may explain the contradictory results in the literature. Thus, to advance the areas of research further, longitudinal studies involving larger number of patients are required to identify the major pathogenic factors.

Origins and complexes: the initiation of DNA replication

Eukaryotic DNA is organized for replication as multiple replicons. DNA synthesis in each replicon is initiated at an origin of replication. In both budding yeast, Saccharomyces cerevisiae and fission yeast, Schizosaccharomyces pombe, origins contain specific sequences that are essential for initiation, although these differ significantly between the two yeasts with those of S. pombe being more complex then those of S. cerevisiae. However, it is not yet clear whether the replication origins of plants contain specific essential sequences or whether origin sites are determined by features of chromatin structure. In all eukaryotes there are several biochemical events that must take place before initiation can occur. These are the marking of the origins by the origin recognition complex (ORC), the loading onto the origins, in a series of steps, of origin activation factors including the MCM proteins, and the initial denaturation of the double helix to form a replication "bubble". Only then can the enzymes that actually initiate replication, primase and DNA polymerase-alpha, gain access to the template. In many cells this complex series of events occurs only once per cell cycle, ensuring that DNA is not re-replicated within one cycle. However, regulated re-replication of DNA within one cell cycle (DNA endoreduplication) is relatively common in plants, indicating that the "once-per-cycle" controls can be overridden.

Comparing self-reported measures of diabetes care with similar measures from a chart audit in a well-defined population

The objective of this study was to compare self-reported measures of diabetes care with measures derived from medical records in a well-defined population. Diabetes measures were collected through a 1997 Behavioral Risk Factor Surveillance System telephone survey of American Indians living on or near 7 Montana reservations (N = 398) and were compared with data collected from charts of a systematic sample of American Indians with diabetes seen in 1997 at Indian Health Service (IHS) facilities. Survey respondents were more likely to report a duration of diabetes > or = 10 years (44 vs 31%), annual dilated retinal exam (75 vs 59%), and an influenza immunization in the past year (73 vs 57%) compared with estimates from the chart audit. Estimates of pneumococcal immunization (88 vs 42%), annual cholesterol screening (86 vs 69%), and overweight, based on body mass index (67 vs 50%), were significantly higher from the chart audit. No significant differences were found between the survey respondents and the chart audit data for annual foot exams (65 vs 61%), annual blood pressure checks (98 vs 93%), high cholesterol (35 vs 41%), and high blood pressure (54 vs 64%). These findings suggest that self-reported data may over and underestimate specific measures of diabetes care.

Lysostaphin expression in mammary glands confers protection against staphylococcal infection in transgenic mice

Infection of the mammary gland, in addition to causing animal distress, is a major economic burden of the dairy industry. Staphylococcus aureus is the major contagious mastitis pathogen, accounting for approximately 15-30% of infections, and has proved difficult to control using standard management practices. As a first step toward enhancing mastitis resistance of dairy animals, we report the generation of transgenic mice that secrete a potent anti-staphylococcal protein into milk. The protein, lysostaphin, is a peptidoglycan hydrolase normally produced by Staphylococcus simulans. When the native form is secreted by transfected eukaryotic cells it becomes glycosylated and inactive. However, removal of two glycosylation motifs through engineering asparagine to glutamine codon substitutions enables secretion of Gln(125,232)-lysostaphin, a bioactive variant. Three lines of transgenic mice, in which the 5'-flanking region of the ovine beta-lactoglobulin gene directed the secretion of Gln(125,232)-lysostaphin into milk, exhibit substantial resistance to an intramammary challenge of 104 colony-forming units (c.f.u.) of S. aureus, with the highest expressing line being completely resistant. Milk protein content and profiles of transgenic and nontransgenic mice are similar. These results clearly demonstrate the potential of genetic engineering to combat the most prevalent disease of dairy cattle.

Comparison of the lipoprotein, carbohydrate, and hemostatic effects of phasic oral contraceptives containing desogestrel or levonorgestrel

Desogestrel (DSG) is a less-androgenic progestogen than levonorgestrel (LNG). This difference in androgenicity may be responsible for observed differences in metabolic effects between oral contraceptive (OC) formulations containing almost equivalent estrogen doses but with either DSG or LNG as a progestogen. To test the hypothesis, a prospective 9-month randomized comparison of plasma lipids, glucose, insulin, hemostasis, and sex hormone binding globulin (SHBG) was conducted in 66 healthy women using phasic formulations of OCs containing either DSG (DSG-OC) or LNG (LNG-OC). The study results showed that SHBG increased 3-fold with DSG-OC and 2-fold with LNG-OC. DSG-OC increased HDL-C, HDL(2)-C and HDL(3)-C; LDL-C decreased transiently. LNG-OC decreased HDL(2)-C and increased HDL(3)-C; HDL-C was unchanged and LDL-C decreased transiently. Both formulations increased VLDL-C and triglycerides, more with DSG-OC, but apolipoprotein B levels increased equally. Apo A-I and A-II increased more with DSG-OC than with LNG-OC. Neither formulation altered Lp(a) or fasting glucose and insulin levels. Postprandially, both formulations decreased glucose and increased insulin responses, but to an equivalent degree. Both OCs slightly enhanced procoagulant and profibrinolytic parameters to the same extent except for internally compensating decreases in Factor V and protein S with DSG-OC. In summary, at almost equivalent estrogen doses, a phasic OC containing DSG compared with LNG has a less androgenic effect on lipoproteins and SHBG, similar effects on hemostatic parameters with lower protein S and factor V activity and equivalent effects on carbohydrate metabolism. The lipoprotein, SHBG, and protein S and factor V differences are likely due to the lesser androgenicity of DSG allowing for a greater expression of the dose of estrogen.

Applying the diabetes quality improvement project indicators in the Indian Health Service primary care setting

OBJECTIVE

With publication of the Diabetes Quality Improvement Project (DQIP) measures, the Indian Health Service National Diabetes Program applied the DQIP format to its IHS Diabetes Care and Outcomes Audit for comparison and benchmarks.

RESEARCH DESIGN AND METHODS

Since 1986 the IHS Diabetes Care and Outcomes Audit has been conducted by medical record review in >75% of IHS and tribal facilities. Each year systematic random sample of charts is drawn from local diabetes registries. Chart reviews are conducted by, trained professionals according to standard definitions and instructions. Abstracted data are entered into a microcomputer-based epidemiologic software package. Local, regional, and national rates are constructed for each item. During the period 1995-1997, 150 facilities submitted data for compilation, representing participation from all 12 IHS administrative regions. The IHS Diabetes Care and Outcomes Audit collected virtually all of the DQIP measures, with the exception of LDL cholesterol (which was added to the record review in 1998).

RESULTS

In 1995, 1996, and 1997, a total of 9,557, 9,985, and 9,626 individuals, respectively, were included in the total IHS audit sample. The reviews for 1995, 1996, and 1997 revealed that of all subjects: 55, 65, and 80%, respectively, had more than one HbA1c test during the year (P < 0.001); 42, 38, and 34%, respectively; had a high-risk HbA1c (>9.5%) (P < 0.001); 83, 81, and 84%, respectively, were tested for macroproteinuria (P < 0.11) and 16, 17, and 23%, respectively were tested for microproteinuria (P < 0.001); total cholesterol was assessed in 80, 81, and 85%, respectively (P < 0.001), and corresponding proportions of those with values <5.17 mmol/l were 48, 50, and 52%, respectively; triglyceride values were measured for 75,75, and 80%, respectively (P < 0.001), and the corresponding median triglyceride levels were 199, 198, and 193 mg/dl, respectively (P < 0.001); the proportion of clients with a blood pressure <140/90 mmHg was 64, 64, and 66%, respectively (P < 0.05); 55, 56, and 55%, respectively, had a dilated eye exam (P < 0.053); and the proportion of clients who had a comprehensive foot exam were 59, 59, and 61%, respectively (P < 0.05).

CONCLUSIONS

The DQIP accountability and quality improvement measures could be easily applied to the IHS Diabetes Care and Outcomes Audit, and the process can prove to be practical. However, data alone are not sufficient to effect change. Use of the measures to ensure that the quality of care improves must also be stressed, because measuring alone will not guarantee such improvement.

A multi-state outbreak of tuberculosis among members of a highly mobile social network: implications for tuberculosis elimination

SETTING

Baltimore, Maryland.

OBJECTIVE

To describe a tuberculosis (TB) outbreak among a highly mobile population and the efforts required to control it.

DESIGN

Epidemiologic outbreak investigation.

RESULTS

Between June 1998 and January 2000, 20 TB outbreak cases were identified, of which 18 were culture-confirmed. Seventeen isolates of Mycobacterium tuberculosis had an identical 11-band DNA fingerprint; another isolate had one additional band and was considered a match. Two cases were diagnosed in New York City; another patient lived primarily in Atlanta, but was diagnosed in Baltimore. Persons in the outbreak were predominantly young (median age 24 years), black, male, infected with the human immunodeficiency virus (HIV), and gay, transvestite or transsexual. Activities common among many TB cases included attending two nightclubs, membership in one of three social 'Houses', attending balls or pageants in East Coast cities, marijuana use, and prostitution. Community outreach, extended contact tracing, DNA fingerprinting, directly-observed therapy, and expanded use of preventive therapy were utilized to assess and control the outbreak. During the outbreak period the Baltimore City TB rate declined by 10%. However, additional public health personnel were required to control the outbreak, resulting in a 17% increase in TB clinic staff.

CONCLUSION

As TB rates decline, remaining cases are likely to occur in difficult-to-reach populations. Increased resources per case of TB treated will be required to eliminate TB.

Analysis of 114 kb of DNA sequence from fission yeast chromosome 2 immediately centromere-distal to his5

One hundred and fourteen kilobase pairs (kb) of contiguous genomic sequence have been determined immediately distal to the his5 genetic marker located about 0.9 Mb from the centromere on the long arm of Schizosaccharomyces pombe chromosome 2. The sequence is contained in overlapping cosmid clones c16H5, c12D12, c24C6 and c19G7, of which 20 kb are identical to previously reported sequence from clone c21H7. The remaining 93 781 bp of sequence contains 10 known genes (cdc14, cdm1, cps1, gpa1, msh2, pck2, rip1, rps30-2, sad1 and ubl1), 32 open reading frames (ORFs) capable of coding for proteins of at least 100 amino acid residues in length, one 5S rRNA gene, one tRNA(Pro) gene, one lone Tf1-type long terminal repeat (LTR) and one lone Tf2-type LTR. There is a density of one protein-coding gene per 2.2 kb and 22 of the 42 ORFs (52%) incorporate one or more introns. Twenty-one of the novel ORFs show sequence similarities which suggest functions of their products, including a cyclin C, a MADS box transcription factor, mad2-like protein, telomere binding protein, topoisomerase II-associated protein, ATP-dependent DEAH box RNA helicase, G10 protein, ubiquitin-activating e1-like enzyme, nucleoporin, prolyl-tRNA synthetase, peptidylprolyl isomerase, delta-1-pyrroline-5-carboxylate dehydrogenase, protein transport protein, coatomer epsilon, TCP-1 chaperonin, beta-subunit of 6-phosphofructokinase, aminodeoxychorismate lyase, a phosphate transport protein and a thioredoxin.

Comparison of telomerase levels before and after differentiation of two cell lines of human neuroblastoma

BACKGROUND

Telomerase is the enzyme that is responsible for maintaining telomere length in human germ cells, tumor cells, and immortalized cells. Its specific role in the immortilization process is unknown. This study was performed to determined whether the level of telomerase activity in human neuroblastoma cell lines correlated with their level of differentiation. We proposed that as neuroblastoma cells differentiated into more mature or benign cells, the levels of telomerase expression would decrease.

MATERIALS AND METHODS

Two human neuroblastoma cells lines, SK-N-AS and SK-N-DZ, were differentiated using retinoic acid. These cells were assayed for telomerase activity by the telomere repeat amplification protocol (TRAP) before, during, and after treatment with retinoic acid for 8 days. Untreated cells were used for control and were compared to the retinoic acid-treated cells. Differentiation of the cell lines was confirmed by assaying expression of ret mRNA using the reverse-transcriptase polymerase chain reaction (RT-PCR) and gel electrophoresis of the radiolabeled products.

RESULTS

No statistical difference in telomerase activity was noted between control and treated groups.

CONCLUSIONS

While telomerase activity has been shown by others to correlate with tumor aggressiveness in human neuroblastoma cells, the mechanism that is involved appears to be separate from cellular differentiation.