Effect of perifoveal tissue dissection in the management of acute idiopathic full-thickness macular holes

OBJECTIVE

To evaluate the efficacy of perifoveal tissue dissection (PTD) on patients undergoing pars plana vitrectomy for idiopathic macular holes of less than 1-year's duration.

METHODS

Pars plana core vitrectomy was performed on 107 eyes of 104 consecutive patients with acute idiopathic macular holes. One cohort had routine PTD. In the other cohort, no attempt was made to strip preretinal tissue. Follow-up was longer than 6 months (follow-up range, 6 to 36 months).

RESULTS

Overall, 95 (89%) of all macular holes were closed. Visual acuity improved 2 lines or more of the Snellen letter chart in 91 eyes (85%). A postoperative visual acuity of 20/50 or better was achieved in 79 eyes (74%). A transient increase in intraocular pressure (230 mm Hg) developed in 25 eyes (23.4%). In 6 eyes (5.6%) a retinal detachment developed. One eye had retinal pigment epithelial changes and 1 patient reported peripheral field loss. No statistically significant differences were noted between eyes having PTD and those without PTD for any outcome measure.

CONCLUSION

In this series, no beneficial or adverse effect could be demonstrated by performing PTD in eyes undergoing pars plana core vitrectomy for acute idiopathic macular holes.

Ultrasound biomicroscopy in a case of anterior hyaloidal fibrovascular proliferation

The authors describe the use of ultrasound biomicroscopy for the diagnosis and preoperative evaluation of anterior hyaloidal fibrovascular proliferation (AHFVP). Ultrasound biomicroscopy was performed on a 62-year-old man who presented after diabetic vitrectomy with a hyphema, vitreous hemorrhage, and hypotony. Images in the temporal and nasal meridians revealed thickened tissue bands extending from the peripheral retina to the ciliary body, and from the pars plicata to the posterior surface of the iris. A ciliary body epithelium detachment was seen in the nasal meridian. Ultrasound biomicroscopy demonstrated to be a potential tool in the diagnosis and surgical management of AHFVP.

Results after lens extraction in patients with diabetic retinopathy: early treatment diabetic retinopathy study report number 25

OBJECTIVE

To assess the visual results after surgical lens removal in patients with diabetic retinopathy.

DESIGN

A multicenter randomized clinical trial designed to assess the effect of photocoagulation and aspirin in patients with mild to severe nonproliferative or early proliferative diabetic retinopathy and/or macular edema.

PARTICIPANTS

Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, lens surgery was performed on 205 patients (270 eyes) during follow-up that ranged from 4 to 9 years.

OUTCOME MEASUREMENTS

Visual acuity, macular edema status, and degree of diabetic retinopathy. In addition, risk factors associated with lens extraction and with poor postoperative visual acuity (worse than 20/100) were assessed.

RESULTS

The risk of lens extraction increased with increasing age, female sex, and baseline proteinuria. Ocular variables associated with increased risk of lens surgery included poor baseline visual acuity and vitrectomy performed during the course of the study. At 1 year after lens surgery, visual acuity improvement of 2 or more lines from preoperative levels occurred in 64.3% of the operated-on eyes assigned to early photocoagulation and 59.3% of eyes assigned to deferral of photocoagulation. In eyes assigned to early photocoagulation, 46% of eyes achieved visual acuity better than 20/40; 73%, better than 20/100; and 8%, 5/200 or worse at 1 year after surgery. Visual acuity results for eyes assigned to deferral of laser photocoagulation at 1 year were not as favorable; 36% achieved visual acuity better than 20/40; 55%, better than 20/100; and 17%, 5/200 or worse at 1 year after surgery. Evaluation of 1-year postoperative visual acuities for all eyes with mild to moderate nonproliferative diabetic retinopathy at the annual visit before lens surgery showed that 53% were better than 20/40; 90%, better than 20/100; and 1%, 5/200 or worse. However, for eyes with severe nonproliferative or worse retinopathy at the annual visit before lens surgery, only 25% were better than 20/40; 42%, better than 20/100; and 22%, 5/200 or worse at 1 year after lens surgery. There was little change in visual acuity between 1 and 2 years postoperatively. Increased severity of retinopathy and poor visual acuity before surgery were associated with visual acuity of worse than 20/100 at 1 year after surgery. Lens surgery was associated with a borderline statistically significant increased risk of progression of diabetic retinopathy in the adjusted analyses (P = .03). No statistically significant long-term increased risk of macular edema was documented after lens surgery.

CONCLUSIONS

Visual acuity results after lens surgery in patients in the Early Treatment Diabetic Retinopathy Study were better than published results for similar patients. This may be because of more intensive photocoagulation for lesions of diabetic retinopathy in the Early Treatment Diabetic Retinopathy Study than in previously reported studies. Although patients with severe nonproliferative retinopathy or worse before lens surgery had poorer visual results, visual improvement was seen in 55% of these patients at 1-year follow-up. The main causes of poor visual results in eyes after lens surgery were complications of proliferative retinopathy and/or macular edema.

Successful closure of traumatic macular holes

PURPOSE

To establish the efficacy of vitreoretinal surgery without the use of transforming growth factor-beta or autologous platelet concentrate in the repair of traumatic macular holes.

METHODS

This retrospective review consisted of 16 eyes from 16 consecutive patients treated by five vitreoretinal surgeons at a single institution between 1993 and 1997. Intervention included pars plana vitrectomy with creation of posterior vitreous detachment, placement of 14% to 16% C3F8 gas, and postoperative face-down positioning. Ten eyes received intraoperative autologous plasmin to facilitate formation of posterior vitreous detachment. Main outcome measures were anatomic closure rate and visual outcome.

RESULTS

Anatomic closure of the macular holes was achieved in 15 (94%) of 16 eyes, with an average follow-up of 7 months. Six (38%) eyes achieved visual acuity of 20/40 or better. Visual acuity improved by 2 or more lines in 11 (69%) of 16 eyes. The average preoperative logMAR-converted visual acuity of 20/175 improved to 20/60 postoperatively.

CONCLUSION

Traumatic macular holes can be closed successfully with substantial visual recovery without the use of transforming growth factor-beta or platelet concentrate.

Vitrectomy for chronic pseudophakic cystoid macular edema

PURPOSE

We report the results of pars plana vitrectomy for chronic pseudophakic cystoid macular edema unresponsive to medical treatment.

METHODS

Retrospective analysis of 23 consecutive eyes of 23 patients with chronic pseudophakic cystoid macular edema was performed. Eyes with vitreous incarceration into the cataract wound or vitreous-cornea contact were excluded from the study. Preoperatively, all eyes had cystoid macular edema confirmed on fluorescein angiography and were unresponsive to medical treatment. Pars plana vitrectomy was performed using standard techniques and vitreous adhesions to the iris, intraocular lens, or both were lysed if present.

RESULTS

The mean interval between cataract surgery and vitrectomy was 32.3+/-30.9 months (median, 20 months; range, 3 to 110 months). The vitreous was adherent to the iris or intraocular lens in 12 eyes (52.2%) and was present in the anterior chamber with no evidence of adhesions in seven eyes (30.4%). In four eyes (17.4%) the vitreous was posterior to the iris plane with no adhesions to anterior segment structures. The median preoperative best-corrected visual acuity was 20/200, and the median final postoperative best-corrected visual acuity was 20/60 (P<.0001) after a mean follow-up of 30.2+/-31.2 months (median, 14 months; range, 2 to 109 months). Final best-corrected visual acuity improved by a mean of 3.3+/-2.6 Snellen lines, with a median percent change of 70% (mean, 57.3%; range, 0% to 99%). In all 23 eyes the cystoid macular edema resolved postoperatively by biomicroscopic examination in a mean period of 3.3 months (median, 2 months; range, 1 to 12 months).

CONCLUSIONS

In pseudophakic eyes with chronic cystoid macular edema unresponsive to medical treatment, vitrectomy resulted in resolution of the cystoid macular edema with improved visual acuity in some cases. Clinical improvement may occur in eyes with no apparent vitreous disturbance.

Potential utility of left heart contrast agents in diagnosis of myocardial rupture by 2-dimensional echocardiography

This case illustrates the use of intravenous injections of a contrast agent during 2-dimensional echocardiography in a patient with myocardial rupture after myocardial infarction. Intravenous injections of echocardiographic contrast agents may have potential use in the identification of intrapericardial hemorrhage after myocardial infarction caused by myocardial rupture or development of ventricular pseudoaneurysm.

Human diabetic neovascular membranes contain high levels of urokinase and metalloproteinase enzymes

PURPOSE

Retinal neovascularization is one of the leading causes of blindness. A crucial event in this process is the remodeling and penetration of the capillary basement membrane by migrating endothelial cells. This process requires proteolysis of basement membrane components by a variety of proteinases. The objective of the present study was to determine the expression of proteinases in human retinal tissues showing active neovascularization.

METHODS

Epiretinal neovascular membranes surgically removed from patients with proliferative diabetic retinopathy were analyzed by zymography, and the types and amounts of proteinases present in the tissues were determined. Retinas from nondiabetic donor eyes served as control specimens.

RESULTS

Both the high- (54 kDa) and low- (33 kDa) molecular-weight forms of urokinase were present at significantly higher levels in neovascular membranes than in normal retinas. The pro forms of the matrix metalloproteinases (MMP) MMP-2 and MMP-9 were significantly elevated in the neovascular membranes in comparison with levels in normal retinas. In addition, the active forms of these enzymes were present in the membranes, whereas there was no detectable level of the active forms in normal retinas.

CONCLUSIONS

Human diabetic neovascular membranes contain high levels of urokinase and MMP. The increased activity of proteinases in the final common pathway of retinal neovascularization indicates that inhibition of these enzymes may be a useful therapeutic target as an alternative approach in the management of proliferative retinopathies.

A selective difference between human Y-chromosomal DNA haplotypes

DNA analysis is making a valuable contribution to the understanding of human evolution [1]. Much attention has focused on mitochondrial DNA (mtDNA) [2] and the Y chromosome [3] [4], both of which escape recombination and so provide information on maternal and paternal lineages, respectively. It is often assumed that the polymorphisms observed at loci on mtDNA and the Y chromosome are selectively neutral and, therefore, that existing patterns of molecular variation can be used to deduce the histories of populations in terms of drift, population movements, and cultural practices. The coalescence of the molecular phylogenies of mtDNA and the Y chromosome to recent common ancestors in Africa [5] [6], for example, has been taken to reflect a recent origin of modern human populations in Africa. An alternative explanation, though, could be the recent selective spread of mtDNA and Y chromosome haplotypes from Africa in a population with a more complex history [7]. It is therefore important to establish whether there are selective differences between classes (haplotypes) of mtDNA and Y chromosomes and, if so, whether these differences could have been sufficient to influence the distributions of haplotypes in existing populations. A precedent for this hypothesis has been established for mtDNA in that one mtDNA background increases susceptibility to Leber hereditary optic neuropathy [8]. Although studies of nucleotide diversity in global samples of Y chromosomes have suggested an absence of recent selective sweeps or bottlenecks [9], selection may, in principle, be very important for the Y chromosome because it carries several loci affecting male fertility [10] [11] and as many as 5% of males are infertile [11] [12]. Here, we show that one class of infertile males, PRKX/PRKY translocation XX males, arises predominantly on a particular Y haplotypic background. Selection is, therefore, acting on Y haplotype distributions in the population.

Good visual acuity in an adult population with marked posterior segment changes secondary to retinopathy of prematurity

PURPOSE

To show that good visual acuity can be compatible with marked posterior segment changes secondary to retinopathy of prematurity (ROP) in the adult population.

METHODS

A retrospective chart review of adult patients with regressed ROP. We found 14 eyes in 12 patients who were older than 21 years with a visual acuity of 20/60 or better associated with marked posterior segment changes secondary to ROP.

RESULTS

Of the 14 eyes, 11 were myopic, with six eyes having the spherical equivalent of > or = -6.00. Best-corrected visual acuities ranged from 20/15-20/60. One eye had a macular fold. Thirteen eyes had macular ectopia.

CONCLUSIONS

Good vision can be compatible with marked posterior segment changes secondary to ROP in an adult population. This emphasizes the need to follow these patients closely during childhood and treat them promptly for any amblyogenic condition that could prevent them from reaching their full visual potential.

Plasmin enzyme-assisted vitrectomy in traumatic pediatric macular holes

OBJECTIVE

This study aimed to evaluate the benefit of plasmin enzyme-assisted macular hole surgery on a consecutive series of pediatric patients with traumatic macular holes.

DESIGN

Prospective noncomparative case series operated on at William Beaumont Hospital between July 13, 1996, and November 16, 1996, and observed for at least 6 months.

PARTICIPANTS

During this interval, the authors operated on four eyes from four consecutive patients who were 14 years of age or younger with traumatic macular holes.

INTERVENTION

The patients underwent plasmin enzyme-assisted pars plana vitrectomy with membrane peeling, fluid-gas exchange, and postoperative positioning. The enzyme used was 0.4 international unit (IU) of autologous plasmin enzyme.

MAIN OUTCOME MEASURES

Snellen lines of improvement in visual acuity and rate of final visual acuity of 20/40 or greater, and incidence of complications and reoperations were measured.

RESULTS

All four macular holes were closed successfully. Follow-up was from 6 to 12 months. There were no reoperations. Visual acuity improved from four to eight lines in all eyes. Three eyes (75%) achieved a postoperative visual acuity of 20/40 or better. Three eyes (75%) had transient, posterior, subcapsular cataracts develop: two of the eyes after surgery and one as a result of the initial injury.

CONCLUSION

The treatment of pediatric traumatic macular holes with plasmin enzyme-assisted vitrectomy, membrane peeling, and gas-fluid exchange resulted in closure of the macular holes with significant visual improvement.

Adrenoleukodystrophy: unusual clinical and radiographic manifestation

Adrenoleukodystrophy is an X-linked recessive peroxisomal disorder, characterized by progressive neurologic deterioration due to cerebral white matter demyelination and adrenal insufficiency. Onset is usually in childhood between ages 5 and 10, and its course is fatal within approximately 5 years. Initial symptoms are behavioral, gait, and auditory disturbances and may be a diagnostic dilemma. Abnormally raised plasma very long chain fatty acids (VLCFA) are diagnostic; computed tomography and magnetic resonance imaging findings show symmetrical occipital white matter lesions which progress in a rostralcaudal direction.

Comparison of recombinant transforming growth factor-beta-2 and placebo as an adjunctive agent for macular hole surgery

OBJECTIVE

This study aimed to compare the visual and anatomic results of macular hole surgery in eyes treated with recombinant transforming growth factor-beta-2 (TGF-beta2) or placebo.

DESIGN

The design was a prospective, multicenter, randomized, double-masked, placebo-controlled clinical study.

PARTICIPANTS

One hundred thirty eyes with idiopathic macular holes of 1 year or less and a refracted Early Treatment Diabetic Retinopathy Study visual acuity of 20/80 or worse were treated with 1.1 microg recombinant TGF-beta2 or placebo to the macular hole after fluid-gas exchange.

INTERVENTION

The effect of recombinant TGF-beta2 as an adjunctive agent for macular hole surgery was evaluated.

MAIN OUTCOME MEASURES

Closure of the macular hole and change in visual acuity at 3 months were measured.

RESULTS

The 3-month visits were completed for 120 eyes. The macular hole was closed at 3 months in 35 (61.4%) of 57 eyes treated with placebo and 49 (77.8%) of 63 eyes treated with recombinant TGF-beta2 (P = 0.08). The mean visual acuity gain was +6.4 letters in eyes receiving placebo and +8.9 letters in eyes treated with recombinant TGF-beta2 (P = 0.27). Visual acuity improved 2 or more lines in 23 (40.4%) of 57 eyes treated with placebo and 30 (47.6%) of 63 eyes treated with recombinant TGF-beta2 (P = 0.42). Intraocular pressure elevation greater than 30 mmHg was more common 2 weeks after surgery in eyes treated with recombinant TGF-beta2 (P < 0.001).

CONCLUSIONS

Recombinant TGF-beta2 resulted in a similar proportion of successful closure of macular holes as placebo. There was no statistically significant visual acuity benefit with the use of recombinant TGF-beta2 for the treatment of macular holes.

Video technology and children's evidence: international perspectives and recent research

Research has shown that children can be as competent and reliable as adults as eyewitnesses of crime, if questioned in an appropriate manner. However, there is considerable variation between, and within, countries in the way in which child witness evidence is accepted in criminal cases. This article reviews the legal facilities that exist for young witnesses in countries such as the United States, England & Wales, Canada and Australia. Particular emphasis is placed on recent research into the use of video technology by the courts in child abuse cases--namely testimony with a live video link or a pre-recorded interview in place of live, open court evidence. Studies into the use of live link and videotaped interviews have shown that these innovations could help to reduce the trauma of testifying for children and could lead to better quality evidence from the child. However, there is considerable concern among legal and child protection professionals about the relative lack of impact of video testimony when compared with live, in-court testimony. Research has uncovered significant support among legal professionals towards using curtained partitions 'screens' to allow a child witness to testify within the courtroom without allowing the child to see, or be distracted by, the accused. There is also widespread concern about the questioning techniques used in videotaped interviews and with the live link. Future implications for the use of video testimony are also discussed.

Macular hole surgery without using adjunctive additives

BACKGROUND AND OBJECTIVE

To evaluate the efficacy of performing surgical techniques for macular holes without using adjunctive additives.

PATIENTS AND METHODS

A prospective study was completed of consecutive eyes treated for macular holes of 1 year or less duration that had not had previous vitreous surgery. The best-corrected visual acuity and hole flattening were determined.

RESULTS

Postoperative flattening of the hole was achieved in 39 (91%) of 43 eyes, with at least a 50% reduction of the minimum resolvable visual angle (3-line visual increase) in 65% of the eyes and a final vision of 20/40 or better in 40% of the eyes during the follow-up interval (mean 10.6 months).

CONCLUSIONS

The success rate of current macular hole surgical techniques suggests that adjunctive additives may not be necessary for most cases. Thus, new treatment modalities need to be evaluated with carefully controlled studies.

Vitrectomy for retained lens fragments after phacoemulsification

PURPOSE

Posterior lens fragments after phacoemulsification can be a serious complication of cataract surgery. This study is designed to evaluate the clinical features of eyes after pars plana vitrectomy has been performed to remove posteriorly dislocated lens fragments after phacoemulsification.

METHODS

The authors performed a retrospective chart review of 126 consecutive eyes of 126 patients with dislocated lens fragments after phacoemulsification, managed with pars plana vitrectomy at Associated Retinal Consultants of Michigan. These eyes were operated on from January 1986 through January 1996.

RESULTS

The relation of the intervals between cataract surgery and vitrectomy to various postoperative clinical parameters was studied. Clinical features at presentation included elevated intraocular pressure (IOP over 25 mmHg) in 52.4% of the eyes, uveitis in 69.6%, and corneal edema in 50.8%. Initial visual acuity was 20/400 or worse in 73.8% of the eyes. The mean preoperative visual acuity was 20/278 (median, 20/400), whereas the mean final visual acuity was 20/40 (median, 20/50) after a mean follow-up of 18.9 months. Retinal detachments were found in 20 eyes: 7 before vitrectomy and 13 during or after it. After surgery, 44% of eyes achieved a final visual acuity of 20/40 or better and 90% were 20/400 or better. The distribution of best-corrected final visual acuities among the eyes showed statistically significant differences based on the type of intraocular lens (IOL) used, with posterior chamber IOL greater than anterior chamber IOL, and anterior chamber IOL greater than aphakia. Reasons for a poor visual outcome included persistent corneal edema (four eyes), retinal detachment (two eyes), central retinal vein occlusion (two eyes), age-related macular degeneration (two eyes) glaucoma (one year), and endophthalmitis (one eye).

CONCLUSIONS

There were no statistically significant differences between early (< 7 days) and delayed (8 days or more) vitrectomy when increased IOP, corneal edema, choroidal effusions, cystoid macular edema, and visual acuity were analyzed. The use of vitrectomy to remove posteriorly dislocated lens fragments has been shown to be an effective treatment method that significantly reduces the inflammatory response and hastens visual recovery.

Using focus group methodology to develop breast cancer screening programs that recruit African American women

Public communication campaigns are designed to increase the number of women who receive mammograms, breast examinations, and cervical exams. However, these campaigns have failed to recruit sufficient numbers of African American women. Focus group techniques were used to provide data to develop a communication campaign that would increase the knowledge, assess the attitudes, and change behaviors of African American women, aged 40-65, about the aforementioned preventive health practices. The discussions revealed that participants distrusted "clinics" and preferred being examined by "their own" or a private physician. Results further revealed that the personal influence of opinion leaders, combined with interpersonal contacts that encourage preventive care, help influence women to participate in mammography and cervical cancer screening.

Low-Temperature Structure and Magnetic Properties of Tetraphenylarsonium Tetrachloronitridotechnetate(VI)

The crystal structure of [As(C6H5)4] [TcNCl4] was determined at 120 K by X-ray diffraction and at 28 K by neutron diffraction. The crystals are tetragonal, space group P4/n, with a 1260.4(3) and c 773.2(2) pm at 120 K. The [TcNCl4]-anion possesses exact C4v symmetry, with Tc≡N distances of 160.3(2) and 162.5(4)pm at 120 and 28 K respectively. Magnetic susceptibilities were measured on single crystals from 300 to 4.5 K. The results indicate a well behaved S ½ system following the Curie-Weiss law with θ -0.13 K

Stabilization of ribonuclease B activity by concentrated xylose solutions

Ribonuclease B has become a paradigm as a simple example of an N-linked glycoprotein. We have found that certain affinity-purified preparations of this enzyme demonstrated a pronounced tendency to lose activity if stored as dilute aqueous solutions. Such inactivation is accelerated by the presence of NaCl, but can be counteracted by inclusion of high (1 mol/l) concentrations of xylose. Enzyme activity cannot be restored by addition of xylose after storage of the enzyme. In marked contrast to alpha-methyl-mannoside, xylose does not prevent ribonuclease B from binding to concanavalin A and so may be used to stabilize the enzyme during purification by lectin affinity chromatography.

Lens-sparing vitrectomy with perfluorocarbon liquid for the primary treatment of giant retinal tears

PURPOSE

To evaluate the surgical success of vitrectomy without initial lensectomy in the primary treatment of retinal detachment associated with giant tears without proliferative vitreoretinopathy.

METHODS

Thirty-four consecutive phakic eyes with idiopathic giant retinal tears underwent vitrectomy, injection of perfluorocarbon liquid, endolaser, and gas tamponade. Encircling scleral buckling was performed in 14 of 34 patients. Preoperative visual acuity ranged from 20/25 to hand motions. Giant tear size ranged from 90 degrees to 330 degrees. Follow-up ranged from 10 to 64 months.

RESULTS

Anatomic retinal re-attachment was achieved intraoperatively in all eyes. The re-operation rate was 14% for eyes that underwent scleral buckling with the initial vitrectomy and 45% in eyes without primary scleral buckling. In 59% of eyes with cataract formation, 32% underwent cataract surgery with or without intraocular lens implantation. Best-corrected final visual acuity ranged from 20/15 to 20/400.

CONCLUSION

Most phakic eyes with giant retinal tear not associated with proliferative vitreoretinopathy can be re-attached successfully with initial preservation of the lens.

Crystal Structure of Tetraethylammonium Bromopentacarbonyltungstate(0)

The crystal structure of tetraethylammonium bromopentacarbonyltungstate (0), [NEt4] [W(CO)5Br], has been determined by single-crystal X-ray diffraction methods at 22�1°C. Crystals are tetragonal, space group P4/n, with a 9.206(2), c 10.484(2) Ǻ, and Z 2. Full-matrix least-squares refinement gave a final R value of 0.034 for 820 independent reflections. The [W(CO)5Br]- anion possesses exact C4v symmetry, with bond lengths W-Br 2.736(1), W-COtrans 1.93(1) and W-COcis 2.034(6) Ǻ.

Synchronous carcinomas of cervix and ovary: case reports

Four cases of synchronous carcinoma of the cervix and ovary are reported. In all cases the ovarian and cervical tumours were adenocarcinoma. Surgical management was determined by the extent of the tumours and the need for intracavitary radiotherapy. The dilema in determining whether the tumours were separate primaries or one primary with metastasis is discussed.

Determination of the ratios of 239Pu and 240Pu to 241Am for nuclear weapons test sites in Australia

Recent measurements of the plutonium contamination at former nuclear weapons test sites in Australia have used the 59.5 keV gamma ray from the 241Am impurity to estimate levels of 239Pu and 240Pu. Measurements of the activity ratio of 239Pu to 241Am are presented for sites where suitable samples could be collected. Measurements of 240Pu were also made when interferences from fission products were absent. All measurements were made using a planar Ge detector of sufficient resolution to separate the 51.6 keV 239Pu gamma ray from the Ge K x-ray escape peaks and Compton scattering continuum from the much stronger 59.5 keV 241Am gamma ray. Results are given for most of the plutonium-contaminated sites in Australia.

Platelet activation during hand vibration

The level of beta-thromboglobulin, the circulating platelet aggregate ratio and platelet sensitivity to aggregation with adenosine 5'-diphosphate (ADP) and collagen were assessed in 12 control subjects, 16 patients with vibration white finger (VWF) and 15 patients with primary Raynaud's disease; this was done before and after a 1-min exposure to hand vibration. The beta-thromboglobulin level increased significantly in controls, from a median (interquartile range) of 35.5 (22-47) to 47.5 (27-52) ng/ml, and in the VWF group from 44.0 (39-60) to 47.5 (42-109) ng/ml (P < 0.005). Vibration had no effect on circulating platelet aggregate ratio in any group. The platelets of normal subjects tended to be more sensitive to aggregation with low-dose ADP (1 mmol/l) than those of patients with VWF or primary Raynaud's disease. Significant change occurred in the lag phase of the aggregation response to vibration in the control group at an ADP concentration of 2 and 5 mmol/l. These results indicate that intravascular platelet aggregation occurs as a result of exposure to vibration. Platelet sensitivity to aggregation with ADP may be decreased in patients with VWF or established Raynaud's disease.

Alpha-crystallin: molecular chaperone and protein surfactant

Bovine lens alpha-crystallin has recently been shown to function as a molecular chaperone by stabilizing proteins against heat denaturation (Horwitz, J. (1992) Proc. Natl. Acad. Sci. USA, 89, 10449-10453). An investigation, using a variety of physico-chemical methods, is presented into the mechanism of stabilization. alpha-Crystallin exhibits properties of a surfactant. Firstly, a plot of conductivity of alpha-crystallin versus concentration shows a distinct inflection in its profile, i.e., a critical micelle concentration (cmc), over a concentration range from 0.15 to 0.17 mM. Gel chromatographic and 1H-NMR spectroscopic studies spanning the cmc indicate no change in the aggregated state of alpha-crystallin implying that a change in conformation of the aggregate occurs at the cmc. Secondly, spectrophotometric studies of the rate of heat-induced aggregation and precipitation of alcohol dehydrogenase (ADH), beta L- and gamma-crystallin in the presence of alpha-crystallin and a variety of synthetic surfactants show that stabilization against precipitation results from hydrophobic interactions with alpha-crystallin and monomeric anionic surfactants. Per mole of subunit or monomer, alpha-crystallin is the most efficient at stabilization. alpha-Crystallin, however, does not preserve the activity of ADH after heating. After heat inactivation, gel permeation HPLC indicates that ADH and alpha-crystallin form a high molecular weight aggregate. Similar results are obtained following incubation of beta L- and gamma-crystallin with alpha-crystallin. 1H-NMR spectroscopy of mixtures of alpha- and beta L-crystallin, in their native states, reveals that the C-terminus of beta B2-crystallin is involved in interaction with alpha-crystallin. In the case of gamma- and alpha-crystallin mixtures, a specific interaction occurs between alpha-crystallin and the C-terminal region of gamma B-crystallin, an area which is known from the crystal structure to be relatively hydrophobic and to be involved in intermolecular interactions. The short, flexible C-terminal extensions of alpha-crystallin are not involved in specific interactions with these proteins. It is concluded that alpha-crystallin interacts with native proteins in a weak manner. Once a protein has become denatured, however, the soluble complex with alpha-crystallin cannot be readily dissociated. In the aging lens this finding may have relevance to the formation of high molecular weight crystallin aggregates.

Exercise technetium-99m sestamibi tomography for cardiac risk stratification of patients with stable chest pain

BACKGROUND

This study was designed to evaluate the prognostic value of symptom-limited maximal exercise treadmill testing with tomographic technetium-99m sestamibi (MIBI) myocardial imaging in patients referred for evaluation of stable angina. Exercise stress thallium-201 myocardial imaging provides prognostic information in coronary artery disease subsets including patients with stable chest pain. The prognostic value of exercise technetium-99m MIBI myocardial tomography has not been established.

METHODS AND RESULTS

Of 548 consecutive patients with stable angina pectoris who underwent maximal exercise treadmill stress testing in combination with a same-day "rest-stress" tomographic technetium-99m MIBI myocardial imaging protocol, 521 patients were followed for 13 +/- 5 months to determine the univariate and multivariate variables associated with cardiac events and to define their cardiac event-free survival. Ten patients were lost to follow-up (98% complete), and 17 who had coronary revascularization within 6 months of testing were excluded. Major cardiac events occurred in 24 patients (9%)--nonfatal myocardial infarction in 11 and cardiac death in 13. Univariate Cox survival analysis demonstrated significant relative risk (RR) and 95% confidence intervals (CI) for exercise ST segment depression (RR = 2.3; 95% CI, 1.0 to 5.3), an abnormal MIBI scan (RR = 13.8; 95% CI, 1.9 to 102.3), and a reversible MIBI perfusion defect (RR = 3.2; 95% CI, 1.4 to 7.5). Multivariate models demonstrated that both exercise MIBI perfusion abnormalities (RR = 11.9; 95% CI, 1.6 to 89.4) and reversible MIBI perfusion defects (RR = 2.9; 95% CI, 1.2 to 7.0) had independent predictive value. During 1 year of follow-up, cardiac events occurred in only 0.5% of patients with normal MIBI scans compared with 7% of those with abnormal MIBI scans (P < .001). One-year, cardiac event-free survival was 92% in patients with reversible MIBI perfusion defects (P < .01 versus normal), 96% in patients with fixed defects (P < .01), and 93% in patients with combined reversible and fixed MIBI myocardial perfusion abnormalities (P < .02).

CONCLUSIONS

As with exercise thallium-201 myocardial imaging, exercise stress technetium-99m MIBI myocardial tomography provides significant independent information concerning the subsequent risk of serious cardiac events (death, myocardial infarction) in patients with stable angina pectoris. The identification of MIBI perfusion abnormalities, in particular, the presence of reversible MIBI defects, was associated with reduced 1-year, event-free survival. The recognized imaging and radiotracer biokinetic differences between thallium-201 and MIBI do not appear to modulate the prognostic value associated with scintigraphic evidence of ischemic myocardial jeopardy in the stable angina population.

Pharmacologic induction of posterior vitreous detachment in the rabbit

OBJECTIVE

To assay the proteolytic activity of plasmin on the vitreoretinal junction and to assess a potential facilitating effect on posterior vitreous detachment.

METHODS

We injected 1 U of plasmin into the vitreous of rabbits. Some eyes underwent vitrectomy after plasmin injection. Electroretinography and electron microscopy were performed.

RESULTS

In plasmin-treated eyes, electroretinography displayed a transient (3 days) decreased b-wave amplitude. Histologic examination demonstrated posterior vitreous detachment in eyes that received intravitreal plasmin followed by vitrectomy.

CONCLUSION

Plasmin may prove to be a useful biochemical adjunct to mechanical vitrectomy.

The survival of platypus in captivity: a reappraisal with recommendations for veterinary management and future research

Data are presented on the duration of survival of platypus held in the collections of the 5 Australian zoos displaying the species over the period 1987-1991. Of 10 living platypus, five had survived for 7 or more years. Similarly, of 10 captive animals that died during the period, six had survived for 6 or more years. Five purpose-caught animals were integrated into captive collections over the period; all of these were alive at the end of 1991. The high survival of captive platypus documented in this study contrasts with the conclusion of Whittington (1991) that the duration of survival of platypus in captivity is generally short. This primarily reflects differences in the nature of the two sets of data: Whittington's analysis was based on incomplete records dating back to 1934, and also categorised as 'managed in captivity' those wild platypus that died at zoos while under veterinary care. A series of recommendations on current captive management issues includes the need for improved veterinary knowledge of platypus.

Prevalence of dental caries and enamel defects in the primary dentition of Antiguan pre-school children aged 3-4 years including an assessment of their habits

In 1989 a national survey was carried out on children aged 3 to 4 years attending nursery schools, to investigate the prevalence of caries experience, nursing bottle caries and enamel defects in the primary dentition, and these children's dentally related habits. In the first part of the study, examination of 482 Antiguan children showed that the dmft and dmfs values were 0.80 and 1.26 respectively, and that 77 per cent of the children were caries free; 4.6 per cent of children had nursing bottle caries; and enamel defects occurred in 24 per cent of children. No significant difference was found in oral health between urban and rural samples. In the second part, which was an interview survey, habits such as thumb sucking (13 per cent), not brushing their teeth (3 per cent), and swallowing fluoride toothpaste (13 per cent) were found among 369 children. In the third (a questionnaire) survey, a response rate of 63 per cent was obtained. Significantly more of the children with nursing bottle caries (78.6 per cent) had the habit of sleeping with a feeding bottle than occurred in caries free children (25.6 per cent), but there was no difference in the infant feeding pattern. The children with enamel defects were breast fed for a shorter period and had an earlier introduction to bottle feeding, compared with children without enamel defects. In the final part of the survey, an assessment of snack eating habits at school, a 58 per cent response rate was achieved. The majority of children often brought healthier snacks, together with daily sugar-rich drinks. Significantly more caries free children brought sugary snacks less frequently than children with caries experience.

Aspirin effects on the development of cataracts in patients with diabetes mellitus. Early treatment diabetic retinopathy study report 16

The Early Treatment Diabetic Retinopathy Study, a randomized clinical trial supported by the National Eye Institute, was designed to assess the effect of photocoagulation and aspirin in 3711 patients with mild to severe nonproliferative or early proliferative diabetic retinopathy. Although the primary goal of the study was to evaluate the effect of photocoagulation and aspirin on diabetic retinopathy, the study also provided an opportunity to evaluate the effects of aspirin on the development of cataract. No evidence showed that aspirin use reduced the risk of development of cataract requiring extraction (4.1% vs 4.3% in patients assigned to aspirin or placebo treatment, respectively; Mantel-Cox P = .77; relative risk, 1.05; 99% confidence interval, 0.73 to 1.51). Aspirin use also did not reduce the risk of less extensive but visually significant lens opacities developing (29.6% vs 28.3%; Mantel-Cox P = .76; relative risk, 0.99; 99% confidence interval, 0.85 to 1.15). Early Treatment Diabetic Retinopathy Study results do not support the hypothesis that aspirin (at a dose of 650 mg/d) reduces the risk of cataract development in this diabetic population.

Applications and limitations of vitreoretinal biopsy techniques in intraocular large cell lymphoma

The cases of 4 patients with clinical signs of intraocular large cell lymphoma are described. Initial cytopathologic examination of vitrectomy specimens failed to establish the malignant character of the vitreous infiltrates. Three of the four patients eventually developed solid central nervous system tumors, intracranial biopsy samples of which revealed large cell lymphoma, 13 months to 42 months after initial examination. In one patient, transscleral retinochoroidal biopsy confirmed the diagnosis at the same time as negative vitreous cytologic examination. Results of cytopathologic examination alone of vitreous biopsy specimens may not be sufficient to make a diagnosis in certain cases of large cell lymphoma that are subsequently documented by CNS biopsy. Careful attention should be paid to the handling, processing, and interpretation of vitrectomy specimens from patients suspected of having intraocular large cell lymphoma. Consideration should be given to immunocytologic staining and interpretation by centers that are highly experienced in vitreous cytopathology.

Assessment of loneliness at school among children with mild mental retardation

This study was designed to determine whether children with mild mental retardation understand the concept of loneliness, whether their feelings of loneliness at school can be reliably assessed, and whether there are differences in loneliness between children with and without mental retardation. Results from a sample of 62 students with mild mental retardation and 62 students without retardation, ages 8 through 13, indicated that (a) high percentages of both groups understood what loneliness means, (b) a loneliness questionnaire yielded satisfactory internal reliability with both groups, and (c) boys but not girls with mental retardation reported significantly more loneliness than did children without mental retardation. Suggestions were made for future research on loneliness in school settings.

Atrial pacing with two-dimensional echocardiography for evaluation of chest pain: comparison with thallium 201 scintigraphy

Atrial pacing was performed with two-dimensional (2-D) echocardiography and thallium 201 scintigraphy in 40 men with stable chest pain. Coronary angiography showed significant (one or more lesions greater than or equal to 50%) coronary artery disease (CAD) in 36 patients and no or insignificant CAD in 4. Two dimensional echocardiography showed a left ventricular wall motion abnormality (WMA) either at rest or with pacing in 28 (78%) patients with CAD, with 17 (47%) showing a new or worsened WMA with pacing. A thallium scan showing abnormality (reversible or fixed perfusion defect) was seen in 26 (72%) patients with CAD; 18 (50%) had a reversible defect. In all, 34 of the 36 patients with CAD (94%) had a WMA, a perfusion defect, or both (specificity 50%). Occurrence of both a WMA and a perfusion defect in individual segments ranged from 10 of 25 patients with septal abnormalities to 0 of 12 with abnormalities of the lateral segment. Sensitivity of 2-D echocardiography for identifying CAD in specific vessels was 81% for the left anterior descending (LAD) artery, 30% for the right coronary artery, and 20% for the circumflex artery (both p less than .001 compared with the LAD artery). Corresponding sensitivities for thallium 201 imaging were 54% (p less than .05 compared with 2-D echocardiography), 27%, and 8% (both p less than .05 compared with the LAD artery). When combined with atrial pacing, 2-D echocardiography and thallium 201 perfusion imaging are of similar value for diagnosing the presence of CAD in patients with stable chest pain. Two-dimensional echocardiography is superior to thallium 201 imaging for identifying the presence of significant CAD in the LAD artery, but both tests are limited in their ability to detect lesions of the right coronary or circumflex arteries.

Two-dimensional, spectral Doppler, and color flow imaging in adults with acquired and congenital cor triatriatum

Four adult patients ranging in age from 37 to 72 years with cor triatriatum diagnosed by two-dimensional, spectral Doppler, and color flow imaging are presented, including a previously undescribed "acquired" form after orthotopic heart transplantation and the oldest documented patient with cor triatriatum. The echocardiographic features of cor triatriatum with use of surface and transesophageal imaging are reviewed, with particular emphasis on the color flow findings. Color flow imaging has simplified the diagnosis and assessment of cor triatriatum, including the demonstration of other often-associated congenital cardiac anomalies.

Preparation and Structure of Dibromobis(N,N-diethyldithiocarbamato)-thionitrosyltechnetium(III)

The title compound, [Tc (NS)(S2CNEt2)2Br2], has been prepared by the reaction of [ TcN (S2CNEt2)2] with SOBr2, and its crystal structure has been determined by single-crystal X-ray diffraction methods at 23�1°C. Crystals are orthorhombic, space group Pnma , with a 14.864(7), b 15.857(7), c 8.938(4)Ǻ, and Z 4. Full-matrix least-squares refinement gave a final R value of 0.047 for 1685 independent reflections. The technetium atom is seven-coordinate with a distorted pentagonal- bipyramidal coordination geometry. The thionitrosyl ligand and a bromo ligand occupy the axial positions, with the thionitrosyl group exerting a small trans influence with Tc-Brtrans 2.595(1) and Tc-Brcis 2.564(1)Ǻ. The coordination of the thionitrosyl group is essentially linear with Tc -N=S 177.2(7)°, Tc -N 1.754(9), and N=S 1.504(9)Ǻ.

Thallium-201 perfusion imaging with atrial pacing or dipyridamole stress testing for evaluation of cardiac risk prior to nonvascular surgery

Preoperative assessment of cardiac risk using thallium-201 scintigraphy and atrial pacing (n = 42) or dipyridamole stress testing (n = 35) was performed in 77 patients (mean age 65 +/- 7 years), who subsequently underwent elective nonvascular surgery. All patients were at low cardiac risk by clinical criteria; none could perform exercise stress testing due to physical limitations. ST depression consistent with ischemia occurred in 11 patients during atrial pacing and in 1 patient during dipyridamole stress testing (p less than 0.01). Nine patients had reversible perfusion defects with atrial pacing, and 10 patients with dipyridamole stress testing; fixed defects were present in 15 and 8 patients, respectively. Only one patient (fixed perfusion defect with atrial pacing, left main disease on coronary angiography) underwent preoperative coronary revascularization. Two patients subsequently had postoperative cardiac events. One patient (reversible perfusion defect with dipyridamole stress testing) experienced sudden death after a nonvascular procedure, while a second patient (normal thallium images with dipyridamole testing) had a nonfatal myocardial infarction. In patients having atrial pacing or dipyridamole stress testing, thallium-201 scans that are normal or show only a fixed perfusion defect confirm a low risk of cardiac complications following nonvascular surgery. The presence of a reversible perfusion defect does not preclude a postoperative course free of cardiac complications in patients at low cardiac risk by clinical criteria.

Tissue plasminogen activator and penetrating keratoplasty

We report a patient who developed severe intraocular fibrin formation following penetrating keratoplasty and vitrectomy surgery. The fibrin response worsened despite aggressive treatment with topical steroids. On the second postoperative day, 25 micrograms of intracameral tissue plasminogen activator was administered, resulting in rapid resolution of the fibrin response. The graft remained clear. We believe tissue plasminogen activator may be useful in selected cases of severe, recalcitrant postkeratoplasy fibrin formation.