Neuroprotective effects of an adenoviral vector expressing the glucose transporter: a detailed description of the mediating cellular events

Considerable knowledge exists concerning the events mediating neuron death following a necrotic insult; prompted by this, there have now been successful attempts to use gene therapy approaches to protect neurons from such necrotic injury. In many such studies, however, it is not clear what sequence of cellular events connects the overexpression of the transgene with the enhanced survival. We do so, exploring the effects of overexpressing the Glut-1 glucose transporter with an adenoviral vector in hippocampal cultures challenged with the excitotoxin kainic acid (KA). Such overexpression enhanced glucose transport, attenuated the decline in ATP concentrations, decreased the release of excitatory amino acid neurotransmitters, and decreased the total free cytosolic calcium load. Commensurate with these salutary effects, neuronal survival was enhanced with this gene therapy intervention. Thus, the neuroprotective effects of this particular gene therapy occurs within the known framework of the mechanisms of necrotic neuronal injury.

A medical platform for simulation of surgical procedures

Surgery simulation is a promising technique for training of surgical procedures. The overall goal for any surgical simulator is to allow for efficient training of the skills required and to improve learning by giving the user proper feedback. This goal is easier achieved if the training is performed in a realistic environment. Therefore functionality such as soft tissue deformation, tearing and cutting, penetration of soft tissue etc. is necessary. Furthermore, a realistic simulator must provide haptic feedback so that all senses match, that is, there should be a correspondence between what you see and what you feel with your hands. In this paper we describe a medical platform that provides all this functionality. It is based on the Reachln Magma API, which has been extended for surgery simulation. We describe the development of the platform and illustrate the use of it for the development of two different types of surgical simulators, both of which represents work in progress.

The impact of childhood abuse and neglect on adult mental health: a prospective study

This paper examines the impact of three types of victimization in childhood--sexual abuse, physical abuse, and neglect--on lifetime measures of mental health among adults. In contrast to research that relies on retrospective recall of childhood victimization, this work uses a prospective sample gathered from records of documented court cases of childhood abuse and neglect in a midwestern city around 1970. These subjects were interviewed about twenty years later. In addition, this research compares outcomes of the 641 members of the abuse and neglect group with a matched control group of 510 persons who did not have documented cases of abuse or neglect. The results indicate that men who were abused and neglected as children have more dysthymia and antisocial personality disorder as adults than matched controls, but they did not have more alcohol problems. Abused and neglected women report more symptoms of dysthymia, antisocial personality disorder, and alcohol problems than controls. After controlling for stressful life events, however, childhood victimization had little direct impact on any lifetime mental health outcome. This research indicates the importance of adopting an approach that places childhood victimization in the context of other life stressors and of prospective changes over the life course.

Absence of germline and somatic p53 alterations in children with sporadic brain tumors

Cancers of the central nervous system are the most common solid tumors of childhood. Although somatic alterations of the p53 tumor suppressor gene have been implicated in brain tumorigenesis, the role of germline p53 mutations in the development of childhood brain tumors has not been well defined. As a component of an ongoing extensive study of the epidemiology of childhood brain tumors, we prospectively examined the germline and tumor p53 gene status in 85 children without a family history of cancer who were diagnosed with a sporadic malignant central nervous system tumor. Using PCR/single-strand conformational polymorphism analysis and direct DNA sequencing, 85 children were screened for the presence of constitutional p53 sequence alterations in exons 2 and 4 through 11. No mutations were identified. Commonly reported sequence polymorphisms were observed at codon 72, as well as in 2 other previously described nucleotide residues. Forty-four brain tumor samples were available for analysis and of these 40 were paired with peripheral blood. Once again, no p53 mutations were found. Of the 5 germline samples with the 2 common polymorphisms, only one had a paired tumor sample for comparison and the tumor contained the same alteration as the germline. Of note, one tumor, a PNET of the cerebellum (medulloblastoma), showed loss of heterozygosity at codon 72. We can conclude that the frequency of germline and somatic p53 mutations in sporadic childhood brain tumors is very low, probably less than 1%, and there is no need to screen these patients routinely for their germline p53 status. However, the potential significance of LOH at codon 72 remains to be elucidated.

A genetic epidemiological study of carcinoma of the fallopian tube

OBJECTIVE

The goal of this work was to evaluate the importance of genetic factors in the etiology of fallopian tube cancer.

METHODS

All pathologically confirmed cases of fallopian tube cancer diagnosed in Ontario from 1990 to 1998 were identified from the records of the Ontario Cancer Registry. Living patients were approached to provide information about their family history and to provide a blood sample for testing for mutations in BRCA1 and BRCA2.

RESULTS

A modest increase in the risk of ovarian cancer (relative risk (RR) = 2.2; 95% confidence interval (CI) = 0.4, 6.3) and of early-onset breast cancer (RR = 2.4; 95% CI = 0.6, 6.1) was observed in the first-degree relatives of the fallopian cancer cases. Five of the forty-four cases were positive for a mutation in BRCA1 (11%) and two were positive for a BRCA2 mutation (5%). Five of eighteen women diagnosed at or before age 55 were positive (28%). Two of the seven mutation carriers had a strong family history of breast and ovarian cancer, and three carriers had a modest family history. Three of the forty-four cases were Jewish, and of these, two carried a founder mutation characteristic of this population.

CONCLUSIONS

Fallopian tube carcinoma should be considered to be a clinical component of the hereditary breast-ovarian cancer syndrome, and may be associated with BRCA1 and BRCA2 mutations. Genetic evaluation should be offered to women who present with fallopian tube carcinoma. It is important to consider the risk of fallopian tube carcinoma when prophylactic oophorectomy is performed in high-risk women.

Cellular telephones and cancer--a nationwide cohort study in Denmark

BACKGROUND

Use of cellular telephones is increasing exponentially and has become part of everyday life. Concerns about possible carcinogenic effects of radiofrequency signals have been raised, although they are based on limited scientific evidence.

METHODS

A retrospective cohort study of cancer incidence was conducted in Denmark of all users of cellular telephones during the period from 1982 through 1995. Subscriber lists from the two Danish operating companies identified 420 095 cellular telephone users. Cancer incidence was determined by linkage with the Danish Cancer Registry. All statistical tests are two-sided.

RESULTS

Overall, 3391 cancers were observed with 3825 expected, yielding a significantly decreased standardized incidence ratio (SIR) of 0.89 (95% confidence interval [CI] = 0.86 to 0.92). A substantial proportion of this decreased risk was attributed to deficits of lung cancer and other smoking-related cancers. No excesses were observed for cancers of the brain or nervous system (SIR = 0.95; 95% CI = 0.81 to 1.12) or of the salivary gland (SIR = 0.72; 95% CI = 0.29 to 1.49) or for leukemia (SIR = 0.97; 95% CI = 0.78-1.21), cancers of a priori interest. Risk for these cancers also did not vary by duration of cellular telephone use, time since first subscription, age at first subscription, or type of cellular telephone (analogue or digital). Analysis of brain and nervous system tumors showed no statistically significant SIRs for any subtype or anatomic location.

CONCLUSIONS

The results of this investigation, the first nationwide cancer incidence study of cellular phone users, do not support the hypothesis of an association between use of these telephones and tumors of the brain or salivary gland, leukemia, or other cancers.

Sparing of neuronal function postseizure with gene therapy

Numerous studies have demonstrated that gene therapy interventions can protect neurons from death after neurological insults. In nearly all such studies, however, "protection" consists of reduced neurotoxicity, with no demonstrated preservation of neuronal function. We used a herpes simplex virus-1 system to overexpress either the Glut-1 glucose transporter (GT) (to buffer energetics), or the apoptosis inhibitor Bcl-2. Both decreased hippocampal neuron loss to similar extents during excitotoxic insults in vitro and in vivo. However, the mediating mechanisms and consequences of the two interventions differed. GT overexpression attenuated early, energy-dependent facets of cell death, blocking oxygen radical accumulation. Bcl-2 expression, in contrast, blocked components of death downstream from the energetic and oxidative facets. Most importantly, GT- but not Bcl-2-mediated protection preserved hippocampal function as assessed spatial maze performance. Thus, gene therapeutic sparing of neurons from insult-induced death does not necessarily translate into sparing of function.

Trophoblast cell-specific carcinoembryonic antigen cell adhesion molecule 9 is not required for placental development or a positive outcome of allotypic pregnancies

The carcinoembryonic antigen (CEA) family consists of a large group of evolutionarily divergent glycoproteins. The secreted pregnancy-specific glycoproteins constitute a subgroup within the CEA family. They are predominantly expressed in trophoblast cells throughout placental development and are essential for a positive outcome of pregnancy, possibly by protecting the semiallotypic fetus from the maternal immune system. The murine CEA gene family member CEA cell adhesion molecule 9 (Ceacam9) also exhibits a trophoblast-specific expression pattern. However, its mRNA is found only in certain populations of trophoblast giant cells during early stages of placental development. It is exceptionally well conserved in the rat (over 90% identity on the amino acid level) but is absent from humans. To determine its role during murine development, Ceacam9 was inactivated by homologous recombination. Ceacam9(-/-) mice on both BALB/c and 129/Sv backgrounds developed indistinguishably from heterozygous or wild-type littermates with respect to sex ratio, weight gain, and fertility. Furthermore, the placental morphology and the expression pattern of trophoblast marker genes in the placentae of Ceacam9(-/-) females exhibited no differences. Both backcross analyses and transfer of BALB/c Ceacam9(-/-) blastocysts into pseudopregnant C57BL/6 foster mothers indicated that Ceacam9 is not needed for the protection of the embryo in a semiallogeneic or allogeneic situation. Taken together, Ceacam9 is dispensable for murine placental and embryonic development despite being highly conserved within rodents.

Timely translation during the mouse oocyte-to-embryo transition

In the mouse, completion of oocyte maturation and the initiation of preimplantation development occur during transcriptional silence and depend on the presence and translation of stored mRNAs transcribed in the growing oocyte. The Spin gene has three transcripts, each with an identical open reading frame and a different 3′ untranslated region (UTR). (Beta)-galactosidase-tagged reporter transcripts containing each of the different Spin 3′UTRs were injected into oocytes and zygotes and (beta)-galactosidase activity was monitored. Results from these experiments suggest that differential polyadenylation and translation occurs at two critical points in the oocyte-to-embryo transition - upon oocyte maturation and fertilization - and is dependent on sequences in the 3′UTR. The stability and mobility shifts of ten other maternal transcripts were monitored by reprobing a northern blot of oocytes and embryos collected at 12 hour intervals after fertilization. Some are more stable than others and the upward mobility shift associated with polyadenylation correlates with the presence of cytoplasmic polyadenylation elements (CPEs) within about 120 nucleotides of the nuclear polyadenylation signal. A survey of the 3′ UTRs of expressed sequence tag clusters from a mouse 2-cell stage cDNA library indicates that about one third contain CPEs. We suggest that differential transcript stability and a translational control program can supply the diversity of protein products necessary for oocyte maturation and the initiation of development.

p53 mutations in epithelial ovarian cancers: possible role in predicting chemoresistance

PURPOSE

The investigators undertook a retrospective study to determine (1) whether p53 mutations are predictors of survival in patients with advanced epithelial ovarian cancer, (2) whether p53 status by sequencing is associated with established prognostic indicators, and (3) the agreement of results between direct sequencing of p53 mutations and immunohistochemistry.

MATERIAL AND METHODS

This study was retrospective review of 43 patients with advanced epithelial ovarian cancer treated with surgery and by paclitaxel-based chemotherapy. Clinical data were extracted from the charts. By use of paraffin-embedded blocks, p53 analysis was carried out by (1) direct sequencing and (2) immunohistochemistry. Kaplan-Meier estimates were used for overall and disease-free survivals. To determine whether p53 mutation (sequencing) was related to prognosis and to determine the agreement between p53 abnormalities by sequencing and immunohistochemistry, risk ratios were calculated.

RESULTS

Mean age at diagnosis was 57.4 years. Surgical stages were as follows: 5% were stage IIC, 79% were stage III, and 16% were stage IV. Seventy-seven percent of tumors were serous, and 56% of tumors were grade 3. All patients received paclitaxel-based chemotherapy. Mean disease-free and overall survivals were 16.4 and 22.6 months, respectively. p53 abnormalities were detected by sequencing in 53% of cases and by immunohistochemistry in 70%. Agreement between both techniques was 68%. Patients with stages IIC/IV had a risk of 1.7 of having a p53 mutation by sequencing; grade, histology, disease-free survival and overall survival were not predictive of p53 mutation status.

DISCUSSION

The 54% mutation rate may be underestimated by limiting our analysis to exons 5 to 9. p53 mutation status was not predictive of survival (disease free and overall) or of chemoresistance; this suggests that paclitaxel-based apoptosis is independent of the p53 gene. The concomitant use of cisplatin, an inducer of apoptosis that is dependent on the normal function of p53, makes the interpretation of these results difficult. Histopathologic factors were not statistically associated with p53 status, but more advanced surgical stage and tumor grade were suggestive of higher rates of p53 mutations, implying more aggressive behavior. Finally, the lack of agreement between results obtained by sequencing and immunohistochemistry highlights the limitation of the latter technique and the possibility of underestimating abnormal p53 function. In conclusion, because discrepancies exist between the two techniques, we recommend direct sequencing of exons 4 through 10 to determine the true prevalence of p53 mutation. Furthermore, larger randomized studies are required to elucidate the role of p53 in predicting chemoresponse in advanced epithelial ovarian cancer.

Validity of nutrient estimates by food frequency questionnaires based either on exact frequencies or categories

PURPOSE

The study was designed to assess if category-based Food Frequency Questionnaires (FFQ) could be substituted for exact-frequency based questionnaires.

METHODS

Nutrient estimates on 203 subjects from Toronto, Canada, derived from recoding an exact frequency based 132 item food frequency questionnaire (E-FFQ) into categories were evaluated for validity against a 7-day food record (FR).

RESULTS

Among men, the median Pearson's correlation coefficient (for energy adjusted nutrients) between FR and E-FFQ was 0.53, ranging from 0.26 for thiamin to 0.72 for calcium. The median correlation dropped to a value of 0.40 (range: 0.18 for thiamin to 0. 56 for carbohydrate) when a category-based FFQ (C-FFQ) and FR were compared. Data on women showed a similar pattern; a median correlation of 0.50 from E-FFQ and 0.42 from C-FFQ.

CONCLUSIONS

While the results varied with individual nutrients, overall it is concluded that when validated against food records, the use of exact frequencies in FFQs yielded higher correlation coefficients for most nutrients, and slightly better agreement within quartiles of categories than recoded frequency categories.

The effect of pupil dilation with tropicamide on vision and driving simulator performance

PURPOSE

To assess the effect of pupil dilation on vision and driving ability.

METHODS

A series of tests on various parameters of visual function and driving simulator performance were performed on 12 healthy drivers, before and after pupil dilation using guttae tropicamide 1%. A driving simulator (Transport Research Laboratory) was used to measure reaction time (RT), speed maintenance and steering accuracy. Tests of basic visual function included high- and low-contrast visual acuity (HCVA and LCVA), Pelli-Robson contrast threshold (CT) and Goldmann perimetry (FIELDS). Useful Field of View (UFOV--a test of visual attention) was also undertaken. The mean differences in the pre- and post-dilatation measurements were tested for statistical significance at the 95% level using one-tail paired t-tests.

RESULTS

Pupillary dilation resulted in a statistically significant deterioration in CT and HCVA only. Five of 12 drivers also exhibited deterioration in LCVA, CT and RT. Little evidence emerged for deterioration in FIELDS and UFOV. Also, 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator, leading to improved steering accuracy.

CONCLUSIONS

Pupillary dilation may lead to a decrease in vision and daylight driving performance in young people. A larger study, including a broader spectrum of subjects, is warranted before guidelines can be recommended.

An adenoviral vector expressing the glucose transporter protects cultured striatal neurons from 3-nitropropionic acid

Considerable interest has focused on the possibility of using gene transfer techniques to introduce protective genes into neurons around the time of necrotic insults. We have previously used herpes simplex virus amplicon vectors to overexpress the rat brain glucose transporter, Glut-1 (GT), and have shown it to protect against a variety of necrotic insults both in vitro and in vivo, as well as to buffer neurons from the steps thought to mediate necrotic injury. It is critical to show the specificity of the effects of any such transgene overexpression, in order to show that protection arises from the transgene delivered, rather than from the vector delivery system itself. As such, we tested the protective potential of GT overexpression driven, in this case, by an adenoviral vector, against a novel insult, namely exposure of primary striatal cultures to the metabolic poison, 3-nitropropionic acid (3NP). We observed that GT overexpression buffered neurons from neurotoxicity induced by 3NP.

Comparison of the nutritional composition of diets of persons with fecal incontinence and that of age- and gender-matched controls

PURPOSE

In our clinical and research experience, persons with fecal incontinence anecdotally report altered diet intake to avoid incontinence. The purpose of this study was to compare the dietary intake of 39 persons with fecal incontinence living in the community with that of age- and gender-matched control subjects who had normal bowel function. The diets of both groups were compared with recommended dietary allowances (RDAs) for their constituent nutrients.

METHODS

Subjects prospectively recorded the type, amount, and method of preparing all foods and beverages ingested for 8 consecutive days. Diet records were analyzed using the Nutritionist IV software program.

MAIN OUTCOME MEASURES

The main outcome measures were the amounts and percentage of the RDAs of macronutrients and micronutrients in the subjects' diets.

RESULTS

There were no significant differences in the intake of total kilocalories, protein, fat, dietary fiber, caffeine, or lactose by the fecal incontinence and control groups. The fecal incontinence group had a greater intake of carbohydrates, manganese, and vitamin B(1) compared with the control group. Diets of both groups exceeded 100% of the RDA for protein, phosphorus, iron, sodium, potassium, Vitamins B(1), B(2), B(3), B(12), and C and folate. Diets of both groups had less than 50% of the RDA for biotin, chromium, copper, and manganese but did not differ significantly. The percentages of the RDA for calcium and vitamin D were 84% +/- 6% and 56% +/- 8% for the fecal incontinence group and 90 +/- 8 (P =.6) and 69 +/- 11 for the control group (P =.4).

CONCLUSIONS

The diets of persons with fecal incontinence were similar to those of control subjects with normal bowel function. Both the fecal incontinence and control groups may improve their nutritional patterns by lowering sodium and protein intake and increasing dietary fiber and monounsaturated fat intake. Calcium and vitamin D supplementation may improve dietary deficiencies and lower disease risks. Including a nutritional assessment and consultation in the care of persons with fecal incontinence to improve their general health and prevent disease is recommended, but consideration must be given to altered diet patterns perceived by the patient to prevent fecal incontinence.

Fine mapping and characterization of linked quantitative trait loci involved in the transition of the maize apical meristem from vegetative to generative structures

Quantitative trait locus (QTL) mapping has detected two linked QTL in the 8L chromosome arm segment introgressed from Gaspé Flint (a Northern Flint open-pollinated population) into the background of N28 (a Corn Belt Dent inbred line). Homozygous recombinant lines, with a variable length of the introgressed segment, confirmed the presence of the two previously identified, linked QTL. In the N28 background, Gaspé Flint QTL alleles at both loci induce a reduction in node number, height, and days to anthesis (pollen shed). Given the determinate growth pattern of maize, the phenotypic effects indicate that the two QTL are involved in the transition of the apical meristem from vegetative to generative structures. Relative to the effects of the two QTL in the background of N28, we distinguish two general developmental factors affecting the timing of pollen shed. The primary factor is the timing of the transition of the apical meristem. The second, derivative factor is the global extent of internode elongation. Having separated the two linked QTL, we have laid the foundation for the positional cloning of the QTL with a larger effect.

Delivery of herpes simplex virus amplicon-based vectors to the dentate gyrus does not alter hippocampal synaptic transmission in vivo

Herpes simplex virus type-1 (HSV) amplicon vectors containing neuroprotective genes can alter cell physiology and enhance survival following various insults. However, to date, little is known about effects of viral infection itself (independent of the gene delivered) on neuronal physiology. Electrically-evoked synaptic responses are routinely recorded to measure functional alterations in the nervous system and were used here to assess the potential capability of HSV vectors to disrupt physiology of the hippocampus (a forebrain structure involved in learning that is highly susceptible to necrotic insult, making it a frequent target in gene therapy research). Population excitatory post-synaptic potentials (EPSPs) were recorded in the dentate gyrus (DG) and in area CA3 in vivo 72 h after infusion of an HSV vector expressing a reporter gene (lacZ) or vehicle into the DG. Evoked perforant path (PP-DG) or mossy fiber (MF-CA3) EPSPs slope values measured across input/output (I/O) curves were not altered by infection. Paired-pulse facilitation at either recording site was also unaffected. X-gal-positive granule cells surrounded the recording electrode (PP-DG recording) and stimulating electrode tracts (MF-CA3 recording) in animals that received vector, suggesting that we had measured function, at least in part, in infected neurons. Because of the negative electrophysiological result, we sought to deliver a gene with an HSV amplicon which would affect the measured endpoints, as a positive control. Delivery of calbindin D28kpotentiated PP-DG synaptic strength, indicating that our recording system could detect alterations due to vector expression. Thus, the data indicate that HSV vectors are benign, in regard to effects on synaptic function, and support the use of these vectors as a safe method to deliver selected genes to the central nervous system.

Pavlovian heart rate and jaw movement conditioning in the rabbit: effects of medial prefrontal lesions

An experiment was conducted in which jaw movements (JM) and heart rate (HR) were concomitantly assessed in rabbits during simple Pavlovian conditioning. A 2-s 1200-Hz tone was the conditioned stimulus (CS) and an intraoral 1-cc pulse of 0.5 M sucrose-water solution was the unconditioned stimulus (US). Sham and medial prefrontal (mPFC)-lesioned animals received paired CS/US training with a 70- to 75-dB CS and were compared with sham- and mPFC-lesioned animals that received explicitly unpaired CS/US presentations. The percentages of JM CRs were significantly greater in the paired than the unpaired groups, but mPFC lesions had no effect on this measure. Conditioned HR decelerations occurred only in the paired groups and then only during the first session of training. Moreover, these CS-evoked cardiac decelerations were somewhat attenuated by the mPFC lesion. CS-evoked HR accelerations, which were significantly greater in unpaired than in paired animals, occurred during the four subsequent sessions. These results suggest that a CS-evoked cardioinhibitory process, mediated by the mPFC, is engendered by Pavlovian appetitive conditioning, as has been previously demonstrated for aversive conditioning. However, during JM conditioning these inhibitory changes are quickly replaced by tachycardia, possibly related to increased nonspecific somatomotor activity, since the tachycardia was somewhat greater in the unpaired animals.

How to move things around a hospital: transport logistics at St. Michael's

Ongoing fiscal restraint challenges hospitals to focus their resources primarily on core services. Support services receive much less attention. This article describes the experience of Toronto's St. Michael's Hospital when it re-engineered its transport logistics by consolidating centralized support services into a logistics department and creating new roles and processes to enhance patient care.

Fatty acid chain length determines cholecystokinin secretion and effect on human gastric motility

BACKGROUND & AIMS

Fatty acids induce cholecystokinin (CCK) secretion and modify gastric motility, but the chain length requirements for these effects are not known. Nor is it clear whether the effects of fatty acids on gastric motility in humans are CCK mediated or directly exerted. The aim of this study was to determine the role of fatty acyl chain length in CCK secretion and in influencing gastric motility.

METHODS

Fatty acids were infused into the upper gut in healthy volunteers; plasma CCK was determined by radioimmunoassay. Effects of fatty acids on antral contractility were determined by percutaneous ultrasonography; effects on proximal gastric tone were studied during fundal distention.

RESULTS

Plasma CCK concentration was consistently and similarly elevated by fatty acids with a chain of 12 carbon atoms or longer, whereas those of 11 or fewer carbon atoms failed to increase plasma CCK. A 12-carbon but not a 10-carbon-long chain fatty acid reduced antral contractile amplitude, an effect that was abolished by loxiglumide (a specific CCK-A receptor antagonist). The 12-carbon fatty acid also reduced proximal gastric tone more than the 10-carbon fatty acid.

CONCLUSIONS

A highly specific, chain length-sensitive fatty acid recognition system exists in the proximal gut mediating CCK secretion and gastric motility. An additional, probably CCK-independent, effect of fatty acid also regulates proximal gastric tone.

Correlation between the orbital and intraocular portions of the optic nerve in glaucomatous and ocular hypertensive eyes

BACKGROUND/PURPOSE

It has recently been reported that the retrobulbar optic nerve diameter (OND) and cross-sectional area (ONCSA) are reduced in glaucoma. This study was performed to investigate the correlation between the orbital and intraocular portions of the optic nerve.

METHODS

One eye of 20 volunteers (16 glaucoma subjects, 4 ocular hypertension subjects) underwent optic disc analysis using Heidelberg retinal tomography, and echographic measurements of the retrobulbar optic nerve.

RESULTS

The male-to-female ratio was 6.5:3.5, and the mean age of our sample (+/- SD) was 62.25 +/- 13.7 years. Orbital optic nerve diameter and cross-sectional area correlated significantly and positively with the neuroretinal rim area (Spearman's rank correlation coefficient; OND: rs = 0.488, p = 0.0336; ONCSA: rs = 0.619, p = 0.0079), but not with any other topographical disc data. The retrobulbar optic nerve cross-sectional area-to-disc area ratio (ONCSA/D) was found to have a significant negative correlation with the cup area/disc area ratio (simple regression analysis; r = -3.948, p = 0.046), and a statistically demonstrable positive correlation with the neuroretinal rim area/disc area ratio (r = 0.451, p = 0.046).

CONCLUSION

The results of this study indicate that orbital optic nerve dimensions are a reflection of the neuroretinal rim area of the optic disc. Echographic measurements of the retrobulbar nerve may be additive to the traditional triad of raised intraocular pressure, field defects and glaucomatous optic neuropathy that suggests a diagnosis of glaucoma.