Motion perimetry in anisometropic amblyopia: elevated size thresholds extend into the midperiphery

PURPOSE

Our purpose was to determine whether motion detection abnormalities in patients with anisometropic amblyopia exist and to determine the extent of these abnormalities in the central and midperipheral visual field.

METHODS

We used of motion perimetry to evaluated 10 anisometropic subjects with no manifest strabismus. Each of 44 locations in the visual field corresponding to the test sites of the Humphrey 24-2 program was tested with circular patches of motion (random dot cinematograms) displayed on a computer screen. Stimulus patch size was reduced in a 2/1 staircase manner to determine the smallest patch of motion detectable at each test location (threshold). Data from 15 age-matched normal subjects were used as controls.

RESULTS

Vision in the amblyopic eye ranged from 20/25 to count fingers. The overall mean size threshold for amblyopic eyes was elevated (61% +/- 73%) compared with fellow eyes and age-matched normal eyes (p < 0.03) (i.e., the moving patch of dots in the field had to be larger for it to be detected when viewing with the amblyopic eye). The increase in size threshold was consistent across the visual field and was not greater for central locations.

CONCLUSION

The amblyopia caused by anisometropia is associated with an abnormality in motion detection that extends into the midperiphery of the visual field.

Effects of weight loss on the course of idiopathic intracranial hypertension in women

OBJECTIVE

To determine the role of weight loss in the treatment of idiopathic intracranial hypertension (IIH) in obese women.

METHODS

Chart review of 250 patients with suspected IIH revealed 58 women who met our criteria, did not undergo early surgical intervention, and had adequate documentation of visual status, papilledema, and weight at the baseline evaluation and at 6 months or longer. Patients were divided into two groups based on whether weight loss > or = 2.5 kg occurred during any 3-month interval. Papilledema grade, visual acuity, and visual field grade at 6 months or longer and the time to improve each were recorded.

RESULTS

Mean time in months to improve one grade for papilledema and visual field in one eye was 4.0 versus 6.7 (p = 0.013) and 4.6 versus 12.2 (p = 0.032), respectively, for the 38 patients with weight loss compared with the 20 patients with no weight loss. Papilledema resolved in 28/38 with weight loss (mean, 7.6 months) and 8/20 without weight loss (mean, 10.2 months; p = 0.352). There were no differences in final visual acuity or visual field between the two groups, but the papilledema grade was slightly better in the worst eye in each patient at baseline in the weight loss group (p = 0.03).

CONCLUSIONS

Weight reduction is associated with more rapid recovery of both papilledema and visual field dysfunction in patients with IIH compared with those who do not lose weight.

Luminance contrast and colour contrast related errors in pseudoisochromatic plate identification

PURPOSE

To determine whether differences in luminance contrast and colour contrast are factors in failing to identify American Optical pseudoisochromatic plates (AOPP).

METHODS

We studied two groups of subjects. In 20 normal test subjects with no errors on the AOPP we used cross-polarising filters to darken and then gradually increase perceived luminance of the AOPP until these normal subjects correctly identified the plate. In a second group, to evaluate the relationship between a luminance contrast sensitivity score using Arden plates and AOPP identification, we tested 37 non-colour-deficient subjects who missed zero to five of the AOPP of low colour and luminance contrast (plates 9-12, 15).

RESULTS

Using the cross-polarising filters, we found five plates that required more light to identify (plates 9-12, 15). In the second experiment, we found a significant relationship between the number missed of these five AOPP plates and a decrease in contrast sensitivity (r = 0.91, p < 0.001, Spearman correlation coefficient).

CONCLUSION

Errors in AOPP colour plate detection may be due to loss of ability to perceive colour contrast and possibly luminance contrast.

Proximal and distal histidines in thyroid peroxidase: relation to the alternatively spliced form, TPO-2

The distal and proximal histidines in thyroid peroxidase (TPO), located by amino acid sequence alignment with their known counterparts in myeloperoxidase, are His 239 and His 494, respectively. These histidines lie outside the 57 amino acid peptide (residues 533-589) that is absent in the alternatively spliced form, TPO-2. However, asparagine 579, which very likely forms a stabilizing hydrogen bond with the proximal histidine in TPO, lies within the missing peptide region. The absence of Asn 579 from TPO-2 may be at least partially responsible for the reported lack of activity of this form of the enzyme. Formation of TPO compound I may also depend on Arg 396, based on analogy with the catalytic mechanism previously proposed for the more widely studied plant and fungal peroxidases. A multiple sequence alignment prepared with five mammalian and five invertebrate peroxidases shows complete conservation of Arg 396, as well as residues corresponding to His 239, His 494, and Asn 579 in TPO. The animal peroxidases comprise a family of homologous proteins that differ markedly from the plant/fungal/bacterial peroxidases in primary, secondary, and tertiary structure, yet share with them a common function. Animal peroxidases probably arose independently of the plant/fungal/bacterial peroxidase superfamily and most likely belong to a different gene family. The relation between animal and nonanimal peroxidases may represent an example of convergent evolution to a common enzymatic mechanism.

Long- and short-term variability of automated perimetry results in patients with optic neuritis and healthy subjects

OBJECTIVE

To measure the short- and long-term variability of automated perimetry in patients with optic neuritis and normal subjects.

DESIGN

Prospective case-control design of patients with recovered optic neuritis with intraday and interday repetitions to obtain robust variability measurements. Entry criteria included a corrected pattern SD that was worse than the normal 5% probability level and a mean deviation worse than -3 dB but better than -20 dB. Five Humphrey 30-2 full threshold tests were administered during a 7-hour period (1 test every 2 hours) on the same day and at the same periods on 5 separate days.

SUBJECTS

Seventeen patients with recovered optic neuritis and 10 healthy subjects of similar age.

MAIN OUTCOME MEASURES

Short-term variability and long-term variability for global visual field data.

RESULTS

Patients with optic neuritis demonstrated variations in visual field sensitivity that were outside the entire range of variability for normal controls. These variations occurred for multiple tests performed on the same day at specific times and for tests performed at specific times on different days. There were no consistent patterns of sensitivity changes that could be attributed to time of day. The most dramatic fluctuations occurred in a patient whose visual fields varied from normal to a hemianopic defect from one week to another and from a partial quadrant loss to a hemianopic defect at different times on the same day. Seven of the patients with optic neuritis also demonstrated intermittent vertical step defects.

CONCLUSIONS

Patients with resolved optic neuritis can have large variations in visual field results on different days and at different times on the same day. The variations affect both the severity and the pattern of visual field loss and do not appear to be consistent across patients. These data indicate that care must be taken when automated visual field results in patients with optic neuritis are interpreted. Distinguishing systematic changes in sensitivity from variability requires more than a comparison of the current visual field with the most recent previous visual field.

Asymmetric papilledema in idiopathic intracranial hypertension: prospective interocular comparison of sensory visual function

PURPOSE

Visual loss is the main morbidity of idiopathic intracranial hypertension (IIH). The relationship between papilledema grade and visual loss is unclear. The goal of this study was to determine whether there is a relationship between papilledema grade and visual loss.

METHODS

Fundus photographs of 478 patients with IIH were reviewed, and their degree of papilledema was graded using Frisén's scheme. We identified 46 patients (10%) with IIH and highly asymmetric papilledema, as defined by an interocular difference of two or more grades. Nine of these patients with active asymmetry agreed to return for a series of visual tests. They underwent three visual field tests-Humphrey visual field analyzer 24-2, motion perimetry, and ring perimetry. The perimetry outcome measures were mean deviation, foveal threshold, and means for eccentric zones (3 degrees, 9 degrees, 15 degrees, and 21 degrees). The patients participated also in visual acuity, Farnsworth-Munsell 100-hue, Pelli-Robson contrast sensitivity, and foveal flicker fusion testing. Their relative afferent pupillary defect was graded using neutral density filters.

RESULTS

The intereye comparisons showed vision to be worse in the eye with the high-grade papilledema for all outcome measures. The magnitude of the loss with the perimetry tests increased with eccentricity. The measures of central visual function, although in the normal range, were relatively depressed in the eye with high-grade papilledema.

CONCLUSIONS

Visual loss in patients with asymmetric papilledema caused by IIH was most pronounced in the eye with the higher grade of papilledema. Foveal visual functions, although they remained in the normal range, were also decreased in patients with high-grade papilledema. In patients with high-grade papilledema, visual loss appeared to affect the entire visual field, and the peripheral field showed the most deficit. Our findings showed that high-grade papilledema was associated with visual dysfunction in patients with IIH.

Visual acuity scored by the letter-by-letter or probit methods has lower retest variability than the line assignment method

PURPOSE

The optimal method for scoring visual acuity measures is unknown. Our goal was to determine, in a clinical setting, the method of scoring visual acuity with the lowest test-retest variability.

METHODS

We investigated the effect of three different scoring methods using the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity chart comparing 32 patients with macular disease and 38 age-matched normal subjects. All subjects completed six repetitions of ETDRS charts. Three scoring methods were then used (line assignment, ETDRS or letter-by-letter and probit), the results were converted to log MAR values and the test-retest variabilities analysed.

RESULTS

We found significant differences in variability among the three scoring methods (p < 0.0001). The variability was greatest with the line assignment method and less with the ETDRS and probit methods. The ETDRS and probit methods had similar variabilities. The difference in variability between normals and patients was not statistically significant. There were no differences in the calculated visual acuities among the three methods, only the variabilities. Using the ETDRS or probit methods, the within-test standard deviation was about 0.04 log MAR units (two letters).

CONCLUSION

Test-retest variability of visual acuity measurements is lower using the ETDRS or probit methods than the traditional line assignment method.

Tolerability and Effectiveness of Malaria Chemoprophylaxis with Mefloquine or Chloroquine with or without Co-medication

Background: To determine the relevance of drug interactions with co-medication for effectiveness and tolerability of antimalarial chemoprophylaxis. Method: A database (MALPRO2) on travelers on their flight home from Africa to Europe between July 1988 and December 1991 was reanalyzed. It contains data on prophylaxis with mefloquine (n = 48,264), with chloroquine (6,752), with chloroquine plus proguanil (19,727), and with no prophylaxis (3,871). The comparison of rates of malaria incidence and adverse events (AEs) between users and nonusers of co-medication was expressed by relative risk (RR). Results: Fifty-three percent of travelers (63% of females, 43% of males) used co-medication in all prophylaxis groups, with an average of 1.35 additional drugs per person and about two AEs reported per person. With the exception of antidiarrheals plus mefloquine, malaria incidence with co-medication was lower (RR = 0.8) than without co-medication. In all regimens, the proportion of travelers reporting AEs was about 1.5-fold with co-medication (p<.01); that reporting severe AEs was twice as high as compared to with no co-medication. Mefloquine AE rates for various classes of co-medication were similar to that of chloroquine, with highest AE and severity rates with neuropsychiatric drugs (excluding antiepileptics, RR = 1.9 and 2.9), and lowest rates with cardiovasculars (RR = 1.1 and 1.0). Various co-medications were used with different frequencies in males and females, and the latter reported more AEs. Conclusion: These data suggest that co-medications commonly used by travelers have no significant clinical impact on safety and effectiveness of prophylaxis with mefloquine or chloroquine. Increased frequency and severity of AEs when using co-medication rather is explained by underlying illness.

Central venous catheters coated with minocycline and rifampin for the prevention of catheter-related colonization and bloodstream infections. A randomized, double-blind trial. The Texas Medical Center Catheter Study Group

BACKGROUND

Central venous catheters are a principal source of nosocomial bloodstream infections, which are difficult to control.

OBJECTIVE

To determine the efficacy of catheters coated with minocycline and rifampin in preventing catheter-related colonization and bloodstream infections.

DESIGN

Multicenter, randomized clinical trial.

SETTING

Five university-based medical centers.

PATIENTS

281 hospitalized patients who required 298 triple-lumen, polyurethane venous catheters.

INTERVENTION

147 catheters were pretreated with tridodecylmethyl-ammonium chloride and coated with minocycline and rifampin. Untreated, uncoated catheters (n = 151) were used as controls.

MEASUREMENTS

Quantitative catheter cultures, blood cultures, and molecular typing of organisms to determine catheter-related colonization and bloodstream infections.

RESULTS

The group with coated catheters and the group with uncoated catheters were similar with respect to age, sex, underlying diseases, degree of immunosuppression, therapeutic interventions, and risk factors for catheter infections. Colonization occurred in 36 (26%) uncoated catheters and 11 (8%) coated catheters (P < 0.001). Catheter-related bloodstream infection developed in 7 patients (5%) with uncoated catheters and no patients with coated catheters (P < 0.01). Multivariate logistic regression analysis showed that coating catheters with minocycline and rifampin was an independent protective factor against catheter-related colonization (P < 0.05). No adverse effects related to the coated catheters or antimicrobial resistance were seen. An estimate showed that the use of coated catheters could save costs.

CONCLUSIONS

Central venous catheters coated with minocycline and rifampin can significantly reduce the risk for catheter-related colonization and bloodstream infections. The use of these catheters may save costs.

Prospective study of blunt aortic injury: Multicenter Trial of the American Association for the Surgery of Trauma

BACKGROUND

Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years.

METHODS

This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma.

RESULTS

There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia.

CONCLUSIONS

Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.

Variability in patients with glaucomatous visual field damage is reduced using size V stimuli

PURPOSE

To test the hypothesis that variability of conventional automated perimetry can be reduced using size V stimuli for patients with glaucomatous visual field damage.

METHODS

Ten patients with glaucoma and five age-matched control volunteers were tested with the Humphrey Field Analyzer program 24-2 or 30-2, after which the method of constant stimuli was used to measure frequency-of-seeing curves. This was done by controlling the perimeter with a custom program run by a personal computer. At two widely separated visual field locations on the program 24-2 or 30-2 grid, stimuli were presented in 2 dB intervals to at least 10 dB on either side of the estimated program 24-2 or 30-2 threshold. This protocol was performed for each of three stimulus sizes (Goldmann sizes I, III, and V). For the patients with glaucoma, one test location was chosen in an area of normal visual field sensitivity, the other in an area of 10 to 20 dB loss. Control subjects were tested at the (3 degrees, 3 degrees) and (-21 degrees, -9 degrees) test locations. Fifteen repetitions were performed at each intensity.

RESULTS

Repeated measures analysis of variance showed that variability, as measured by the standard deviation of the cumulative Gaussian function of the fitted frequency-of-seeing curves, was lowest at the abnormal sensitivity test location in the subjects with glaucoma using a size V stimulus. Differences between the results from the V to III and V to I stimuli were statistically significant (size V = 2.9 dB, III = 10.1 dB, I = 10.1 dB). The same trend in estimated standard deviations was present in tests of the area of normal sensitivity (size V = 1.1 dB, III = 1.7 dB, I = 2.0 dB) in subjects with glaucoma and for the control subjects' peripheral test locations, but not for the central location. The smaller reduction in variability between estimated standard deviations of the size I and size III stimuli was not statistically significant at any test location.

CONCLUSIONS

Use of size V stimuli in conventional automated perimetry reduces variability in tests of moderately damaged and normal sensitivity test locations in subjects with glaucoma.

Motion perimetry identifies nerve fiber bundlelike defects in ocular hypertension

OBJECTIVE

To determine whether patients with ocular hypertension (OHT) have elevated motion perimetry thresholds.

DESIGN

Motion perimetry uses a customized computer graphics program to detect the ability to identify a coherent shift in position of 50% of dots in a defined circular area against a background of fixed dots. Motion size threshold is defined as the smallest circular area in which dot motion is detected. Subjects respond by touching the area of the computer monitor with a light pen where motion stimuli are perceived. Reaction times (milliseconds) to stimuli and localization error (number of pixels from target center) are also obtained for each trial.

SETTING

University hospital ophthalmology clinic.

PATIENTS OR OTHER PARTICIPANTS

Twenty-seven patients with OHT and 27 age-matched normal subjects. One eye was tested in each subject.

MAIN OUTCOME MEASURES

Random dot motion stimuli size thresholds and total deviation probability plot data, reaction times, and spatial localization errors.

RESULTS

The patients with OHT had more abnormal test points in the total deviation probability plot analysis compared with the controls (P < .001, chi 2). The abnormal test points were concentrated in the superior and inferior nasal regions. Six subjects had nerve fiber bundlelike defects to motion stimuli. Six subjects (5 overlapping with the probability plot analysis) had abnormal glaucoma hemifield test results. The patients with OHT also had significantly greater localization errors.

CONCLUSION

Motion threshold perimetry may be a more sensitive method to detect visual field abnormalities in OHT than conventional automated perimetry.

Reducing maternal smoking and relapse: long-term evaluation of a pediatric intervention

BACKGROUND

Pediatric well-care visits provide a clinical opportunity to counsel new mothers about their smoking and the deleterious effects of environmental tobacco smoke (ETS) on infant health.

METHODS

Forty-nine Oregon pediatric offices enrolled 2,901 women who were currently smoking or had quit for pregnancy, using a brief survey at the newborn's first office visit. Randomly assigned offices provided advice and materials to mothers at each well-care visit during the first 6 months postpartum to promote quitting or relapse prevention.

RESULTS

The intervention reduced smoking (5.9% vs 2.7%) and relapse (55% vs 45%) at 6-month follow-up, but logistic regression analysis at 12 months revealed no significant treatment effect. The intervention had a positive effect on secondary outcome variables, such as readiness to quit and attitude toward and knowledge of ETS. Multiple logistic regression analysis indicated that husband/partner smoking was the strongest predictor of maternal quitting or relapse.

CONCLUSIONS

A pediatric office-based intervention can significantly affect smoking and relapse prevention for mothers of newborns, but the effect decreases with time. Consistent prompting of the provider to give brief advice and materials at well-care visits could provide a low-cost intervention to reduce infant ETS exposure.

Malaria Prophylaxis in Different Age Groups

Background: There is a perceived increased health risk in senior visitors to malaria endemic countries. Methods: The authors sought to compare effectiveness and tolerability of malaria chemoprophylaxis in senior travelers (>=60 years) with those in younger travelers (20-59 years). The "Malpro 2" database consists of more than 100,000 questionnaires completed by travelers on charter planes returning from East Africa to Europe during July 1988-December 1991. Among them, 9106 (9.1%) of the travelers were 60 years or older, and 84,562 (84.6%) of the travelers reported to be 20-59 years. Variables of demography, travel data, and the effectiveness and tolerability of chemoprophylaxis were compared in the two subgroups. Results: Malaria in Africa was reported by 8 (1/1000) elderly travelers and by 189 (2.2/1000) travelers aged 20-59 years. Adjusting for age, sex, prophylaxis, and duration of stay in Africa in a logistic regression model, malaria was significantly more frequent in younger than in senior travelers (p<.05). Any travel-associated illness was reported by 7.0% in the senior age group and by 13.6% in the younger age group (p<.05). The rates of travelers who indicated they had "side effects" attributable to malaria prophylaxis varied between 9.7% in the elderly and 15.5% in the younger travelers (p<.05). Conclusion: Senior travelers tolerate malaria chemoprophylaxis and visits to the tropics at least as well as younger travelers.

Benefits of the placebo effect in the therapeutic relationship

This paper starts by defining placebos, and describes several placebo effects observed in orthodox medicine. The authors argue that the concept of the placebo effect should not be confined to treatment and medicine alone, but should be extended to the therapeutic relationship itself. They maintain that the interpersonal skills practiced by the complementary therapist are a major factor in producing positive health outcomes. Furthermore, the personality, presentation, and demeanour of the complementary therapist are thought to play a vital part in the promotion of clients' psychological well-being. Other benefits of the placebo effect are discussed, including positive behaviour reinforcement resulting in the client's desire to return to the therapist for further consultation and treatment. The paper concludes by offering several ways in which the placebo effect can be established within the boundaries of the therapeutic relationship.

She could not look to either side

A young woman presented with the recent onset of an inability to move the eyes on a horizontal plane. Examination revealed limited horizontal gaze to the right and a complete left ophthalmoplegia. The limitation of eye movement could not be overcome by the doll's head maneuver. Other signs included bilateral orbicularis oculi weakness and brisk deep tendon reflexes. Her condition gradually improved and two months following the onset of the illness she was symptom free.

The psychometric function and reaction times of automated perimetry in normal and abnormal areas of the visual field in patients with glaucoma

PURPOSE

To study the relationship of reaction time to the psychometric function in normal subjects, normal sensitivity test locations in patients with glaucoma, and test locations with 10 to 20 dB loss in patients with glaucoma.

METHODS

The authors tested 10 patients with glaucoma and 10 age-matched normal volunteers with the Humphrey perimeter, first with program 24-2 and then with the method of constant stimuli to generate frequency of seeing curves. At two widely separated visual field locations on the program 24-2 grid, they presented stimuli in 2-dB intervals, 10 dB either side of the program 24-2 threshold, at 0 dB and 60 dB (15 repetitions per intensity). For the patients with glaucoma, they chose a visual field location with normal sensitivity and a location in an area of 10 to 20 dB loss.

RESULTS

Analysis of variance with post hoc t-tests showed that reaction time (RT) at the 0-dB intensity was prolonged by approximately 90 msec in the abnormal sensitivity test location of patients with glaucoma compared to the control and the glaucoma normal sensitivity groups (P<0.0001). However, this difference was accounted for by only 4 of the 10 patients with glaucoma, reaching 100% of stimuli seen with the brightest stimulus at the moderately damaged test location. Reaction time at the frequency of seeing 50% estimated threshold showed no significant differences among the groups. Prolongation of RT from the 0-dB value was analyzed as a function of increasing attenuation of stimulus intensity. The results fit the equation RT = a + b(Intensity3) for all groups.

CONCLUSIONS

There is no significant difference in RT between normal subjects and patients with glaucoma either at threshold or to suprathreshold stimuli. Reaction time increases after a power function with increasing attenuation of stimulus intensity up to the threshold.

Random dot motion perimetry in patients with glaucoma and in normal subjects

PURPOSE

To determine whether patients with primary open-angle glaucoma have an increase in size thresholds, prolongation of reaction times, and greater localization errors to random dot motion stimuli than normal subjects.

METHODS

Motion perimetry, a computer graphics method of visual field testing, quantitates a subject's ability to detect a correlated shift in position of dots within a defined circular area against a background of fixed dots. We measured motion thresholds, the smallest detectable circular dot motion target, at the Humphrey 24-2 test loci. By using the subject's light-pen responses to the location of the targets, we computed motion size threshold, reaction times, and localization errors (number of pixels from where the subject touched the monitor to the target center). With motion perimetry and conventional automated perimetry, we tested one eye in each of 25 patients with primary open-angle glaucoma and 25 age-matched control subjects. We then generated total deviation pointwise probability plots for the patients with primary open-angle glaucoma.

RESULTS

Patients with primary open-angle glaucoma had increased mean motion size threshold (P < .001) and increased localization errors (P < .002), compared with the control subjects. With the probability plot analysis, there was good correlation of the visual field defects between the two perimetry tests. Additionally, motion perimetry identified nerve fiber bundle-like defects in 12 patients that were not detected with conventional automated perimetry.

CONCLUSIONS

Patients with primary open-angle glaucoma had abnormal motion perception with an increase in spatial localization error.

A retrospective analysis of the in-vitro development of 'spare' human in-vitro fertilization preimplantation embryos using 'in-house' prepared medium and 'Medi-Cult' commercial medium

In-house prepared medium was used routinely in our in-vitro fertilization (IVF) facility prior to the introduction of the commercial 'Medi-Cult' products. A comparative study of the in-vitro development of embryos cultured in two [T6 and Earle's balanced salt solution (EBSS)] human-inactivated serum (HIS)-supplemented media from days 0 to 5 showed that 44.7% (46/103) of the embryos developed to the blastocyst stage in the T6 medium compared with 22.3% (23/103) in EBSS. Following the introduction of the commercial Medi-Cult IVF M2 medium, which is used routinely to culture fertilized eggs from days 0 to 2, new baseline data were required for the in-vitro development of 'spare' embryos from days 2 to 5. When Medi-Cult M3 medium was used, 35.6% (37/104) of the 'spare' day 2 embryos achieved the blastocyst stage. However, if morphologically similar (four normal nucleated blastomeres with no fragmentation) day 2 embryos were selected, an increase in the blastocyst rate to 50.0% (33/66) was achieved. This compared favourably with the 45.0% blastocyst rate (published in the Medi-Cult literature) for M2/M3 medium cultured human embryos. A small series of experiments with T6 + HIS medium and human serum albumin (HSA)-supplemented Ham's F-10, MCDB 302 and M3 media was undertaken to identify a suitable medium which could be used for the culture of M2 medium day 2 embryos. Results show that M2 medium cultured embryos placed in Ham's F-10 medium supplemented with 10 mg/ml HSA gave an acceptable 37.8% (14/45) blastocyst rate. Therefore, this medium could be substituted for M3 medium in an emergency. A total of 483 IVF embryos donated by patients, which were surplus to the therapeutic IVF programme, were used for these studies over a period of 30 months. Late day 2 IVF spare embryos were assigned an embryo score based on a high-power phase-contrast microscopic examination prior to being placed in culture. The embryo score provides an effective in-vitro parameter with which embryos from different patients can be compared. The cleavage and development of individual embryos were monitored on days 2 to 5. In some cases, the continuing normal development and viability of the day 5 cultured embryo were assessed by monitoring the hatching, attachment and outgrowth of the cavitated blastocyst.

Idiopathic intracranial hypertension

Although the cause of IIH remains obscure, it has become clear that loss of visual function is common and patients may progress to blindness. Diagnosis should adhere to the modified Dandy criteria. Recent case-control studies cast doubt on the validity of many frequently cited conditions associated with IIH. Valid associations include obesity, recent weight gain, female gender, vitamin A intoxication, and steroid withdrawal. IIH patient management should include serial perimetry using a sensitive disease-specific strategy. This is done so the proper therapy can be selected and visual loss prevented or reversed.

The structure of Escherichia coli heat-stable enterotoxin b by nuclear magnetic resonance and circular dichroism

The heat-stable enterotoxin b (STb) is secreted by enterotoxigenic Escherichia coli that cause secretory diarrhea in animals and humans. It is a 48-amino acid peptide containing two disulfide bridges, between residues 10 and 48 and 21 and 36, which are crucial for its biological activity. Here, we report the solution structure of STb determined by two- and three-dimensional NMR methods. Approximate interproton distances derived from NOE data were used to construct structures of STb using distance-geometry and simulated annealing procedures. The NMR-derived structure shows that STb is helical between residues 10 and 22 and residues 38 and 44. The helical structure in the region 10-22 is amphipathic and exposes several polar residues to the solvent, some of which have been shown to be important in determining the toxicity of STb. The hydrophobic residues on the opposite face of this helix make contacts with the hydrophobic residues of the C-terminal helix. The loop region between residues 21 and 36 has another cluster of hydrophobic residues and exposes Arg 29 and Asp 30, which have been shown to be important for intestinal secretory activity. CD studies show that reduction of disulfide bridges results in a dramatic loss of structure, which correlates with loss of function. Reduced STb adopts a predominantly random-coil conformation. Chromatographic measurements of concentrations of native, fully reduced, and single-disulfide species in equilibrium mixtures of STb in redox buffers indicate that the formation of the two disulfide bonds in STb is only moderately cooperative. Similar measurements in the presence of 8 M urea suggest that the native secondary structure significantly stabilizes the disulfide bonds.

Using motion perimetry to detect visual field defects in patients with idiopathic intracranial hypertension: a comparison with conventional automated perimetry

Motion perimetry, a method of visual field testing that uses computer graphics to measure motion perception, quantitates a subject's ability to detect a coherent shift in position of dots in a defined circular area against a background of fixed dots. Motion size threshold is defined as the smallest detectable circular target in which dot motion is detected. Subjects respond by touching a computer monitor screen with a light pen, first when they see a target (reaction time) and a second time where motion targets are detected (localization). Reaction time (msec) to the stimulus and localization error (number of pixels from target center) are then calculated and stored. We tested on eye in each of 20 idiopathic intracranial hypertension (IIH) patients and 40 age-matched normal subjects by conventional automated perimetry (Humphrey visual field analyzer, program 24-2) and motion perimetry. Pointwise probability plots of individual abnormal test points for size threshold responses were generated for the IIH patients based on the 95% confidence limits of the normal subject responses. An analysis of the subjects' visual field pairs (motion versus conventional automated perimetry) was performed based on these probability plots. The IIH patients had an elevated mean motion threshold (p < 0.001) and reaction time (p < 0.001) compared with the normal subjects. There were no significant differences for the localization errors. Based on the probability plot analysis, there was good correlation of the visual field defects between the two perimetry tests. In addition, motion perimetry identified nerve fiber bundle-shaped defects in nine patients in whom they were not detected with conventional automated perimetry.