Prevalence of asymptomatic retinal emboli in an Australian urban community

BACKGROUND AND PURPOSE

Because no population-based estimates are available for asymptomatic retinal emboli, we aimed to assess prevalence and associations of this sign in a defined older Australian urban population.

METHODS

A total of 3654 persons aged 49 years or older, representing 82% of residents in an urban area west of Sydney, underwent a detailed eye examination that included medical history, stereo retinal photography, and fasting blood tests including lipids. Retinal emboli were diagnosed clinically and from photographic grading and classified as cholesterol, platelet-fibrin, or calcific in type.

RESULTS

Asymptomatic retinal emboli were found in 51 participants (1.4%; 95% confidence interval [CI], 1.0% to 1.8%). The prevalence was 0.8% in persons aged < 60 years, 1.4% for those aged 60 to 69 years, 2.1% for those aged 70 to 79 years, and 1.5% for those aged 80 years or older. Men had a significantly higher prevalence (2.2%) of retinal emboli than women (0.8%, P < .001) after adjustment for age (odds ratio [OR], 2.7; 95% CI, 1.5 to 4.8). Forty-one emboli (80%) were cholesterol type, 7 (14%) were platelet-fibrin, and 3 (6%) were calcific. Significant associations were found after age-sex adjustment, with hypertension (OR, 2.2; 95% CI, 1.2 to 3.8), a combined history of vascular disease (OR, 2.4; 95% CI, 1.3 to 4.4), past vascular surgery (OR, 3.5; 95% CI, 1.4 to 8.5), and current (OR, 2.2; 95% CI, 1.1 to 4.2) or any (OR, 2.6; 95% CI, 1.2 to 4.3), smoking history. These associations persisted after multivariate analysis. There were no significant associations with diabetes, obesity, or fasting blood test findings.

CONCLUSIONS

This study provides accurate prevalence rates for asymptomatic retinal emboli in the elderly and confirms associations with hypertension, smoking, and vascular disease.

In vivo and in vitro evidence of altered nitric oxide metabolism in the spontaneously diabetic, insulin-dependent BB/Edinburgh rat

1. Altered vasoreactivity may contribute significantly to the pathogenesis of diabetic vascular complications. This study investigated the effect of (a) insulin-related diabetes, and (b) chronic in vivo administration of N(omega)-nitro-L-arginine ester (L-NAME), a nitric oxide (NO) synthase inhibitor, on mean arterial pressure and in vitro vascular reactivity to noradrenaline in mesenteric arterial bed preparations from spontaneously diabetic, insulin-dependent and treated BB rats, the best animal model of insulin-dependent mellitus (IDDM) currently available. Four groups of animals from the Edinburgh colony (BB/E) of spontaneous diabetic BB rats were studied: age-matched (mean +/- s.e. mean = 156 +/- 2d) non-diabetic (glycated haemoglobin = 3.8 +/- 0.1%) and insulin-treated diabetic (glycated haemoglobin = 6.2 +/- 0.5%; duration of diabetes = 56 +/- 4 d) groups were either L-NAME treated (oral dose = 27 +/- 1 mg kg-1 d-1; duration of treatment from 30 until 153 days of age) or untreated. Although our diabetic BB/E rats do not achieve overall normoglycaemia, individual adjustment of the daily insulin dose administered to every diabetic rat achieves better glycaemic control than previous groups studying altered vascular reactivity and endothelial dysfunction in this animal model of diabetes. 2. Mean arterial pressure (measured directly via indwelling carotid arterial cannulae) was not significantly different between non-diabetic (116 +/- 3 mmHg; n = 10) and diabetic (122 +/- 2 mmHg; n = 12) BB/E rats. L-NAME treatment significantly (P < 0.001) increased mean arterial pressure in both groups (165 +/- 6 mmHg; n = 9 and 142 +/- 4 mmHg; n = 6 respectively) but the degree of hypertension observed in L-NAME-treated diabetic rats was significantly (P < 0.01) attenuated compared to non-diabetic rats treated with L-NAME. 3. Mesenteric arterial bed preparations were cannulated under anesthesia, excised and intralumenally perfused ex vivo with noradrenaline (0.2-20 microM). Basal perfusion pressures were not significantly different in mesentery preparations from non-diabetic (27.0 +/- 2.6 mmHg) and diabetic (27.1 +/- 3.2 mmHg) BB/E rats. There was no significant difference in maximal response above basal perfusion pressure (MAX) or pEC50, defined as the negative log of the agonist concentration required to give 50% of the maximal response above basal perfusion pressure, to noradrenaline in untreated non-diabetic (166 +/- 7 mmHg and 5.74 +/- 0.05 respectively) and diabetic (170 +/- 11 mmHg and 5.59 +/- 0.05) BB/E rats. 4. In vivo treatment of non-diabetic and diabetic BB/E rats with L-NAME had no significant effect on basal perfusion pressure (25.9 +/- 4.3 mmHg and 28.5 +/- 3.9 mmHg respectively). L-NAME treatment in vivo increased (P < 0.001) MAX to noradrenaline of non-diabetic rats (224 +/- 8 mmHg) but did not affect the value for diabetic rats (178 +/- 14 mmHg). L-NAME treatment did not alter after the pEC50 values in either group (5.71 +/- 0.05 and 5.65 +/- 0.05). 5. Consistent with previous studies using vascular preparations from spontaneously diabetic BB rats, mesentery preparations from diabetic BB/E rats (n = 12) exhibited a significantly reduced vasodilator response to acetylcholine (F value = 4.4, P < 0.05) across the concentration range studied compared to non-diabetic BB/E rats (n = 12) although there was no significant difference in maximal relaxation (diabetic 53.1 +/- 4.3% vs non-diabetic 55.7 +/- 5.5%) or pEC50, (diabetic 6.92 +/- 0.25 vs non-diabetic 7.49 +/- 0.22). There was no significant (F value = 0.8, P > 0.1) difference in the response to GTN between preparations from non-diabetic and diabetic rats (maximal relaxation: 49.6 +/- 3.7% vs 48.5 +/- 4.3%; pEC50: 7.84 +/- 0.12 vs 7.89 +/- 0.22 respectively). 6. In conclusion, vascular responsiveness to noradrenaline is not impaired in spontaneously diabetic BB/E rats with significantly better glycaemic control than those used in previous studies. However, following chronic L-NAME treatment, diabetic BB/E rats exhibit attenuated hypertension and an absence of enhanced vascular responsiveness to noradrenaline in vitro compared to similarly treated non-diabetic rats. These results, together with the significantly impaired endothelium-dependent vasodilatation and unchanged endothelium-independent vasodilatation in vitro of preparations from diabetic BB/E rats, are consistent with the hypothesis that functional changes in the synthesis and metabolism of NO (rather than altered vascular responsiveness to NO) occur in diabetes. Our results indicate that good glycaemic control alone is insufficient to prevent these abnormalities in NO availability and further studies to characterize the origin of these changes are necessary.

Smoking and age-related maculopathy. The Blue Mountains Eye Study

OBJECTIVE

To assess the associations between stage of age-related maculopathy (ARM) and current, past, and passive smoking.

METHODS

A cross-sectional study of 3654 subjects from a defined geographic area west of Sydney, Australia, identified subjects with late age-related macular degeneration (AMD) and early ARM by ocular examination and detailed grading of retinal photographs. Interviewer-administered questionnaires provided data about smoking history for subjects and spouses. Logistic regression, adjusting for age and sex, and 2-way analysis of variance were used to assess associations.

RESULTS

Current tobacco smoking was significantly associated with late AMD (odds ratio [OR], 3.92), including neovascular AMD (OR, 3.20) and geographic atrophy (OR, 4.54), and early ARM (OR, 1.75). Having ever smoked was significantly associated with late AMD (OR, 1.83) but not early ARM. Passive smoking was associated with increased but insignificant odds for late AMD. The risk was slightly higher among women compared with men for most exposure categories.

CONCLUSIONS

These findings provide convincing evidence that smoking may be causally associated with ARM. The strongest risk was found for current smokers, suggesting potential benefits of targeting education to older people who are current smokers and have signs of early ARM.

Alcohol intake and age-related maculopathy

PURPOSE

To assess associations between alcohol intake and age-related maculopathy.

METHODS

A population-based study of 3,654 subjects identified cases of late age-related macular degeneration, early age-related maculopathy, and any large drusen (larger than 125 microns) by examination and grading of retinal photographs. Interviewer-administered questionnaires provided data on alcohol intake.

RESULTS

Neither total alcohol intake nor intake of beer specifically was significantly associated with age-related maculopathy, although a significant positive association was found between consumption of spirits and early age-related maculopathy.

CONCLUSIONS

These findings provide little evidence that alcohol is causally associated with age-related maculopathy.

Smoking is not a predictor of mortality and morbidity following coronary artery bypass grafting

BACKGROUND

The objective of this study was to determine the significant differences in preoperative and operative characteristics, and postoperative outcomes in patients having coronary artery bypass grafting (CABG) who are smokers and in those who are not smokers.

METHODS

Data were collected prospectively in all (2916) patients having their first CABG. The patients were cared for in a regional medical center by private physicians. No operations were denied because of smoking status. Smokers differed from nonsmokers in several characteristics.

RESULTS

Analysis of morbidity and mortality showed no instance in which smokers fared worse than nonsmokers. Stepwise logistic regression analysis showed that smoking was not predictive of mortality. Smoking was not predictive of morbidity except that it was predictive of less probability of need for intra-aortic balloon pump (7.5% in nonsmokers and 4.7% in smokers). We then created groups of smokers and nonsmokers that were individually matched for age and sex. Analysis of the matched groups of smokers and nonsmokers showed that there was no significant difference in the incidence or magnitude of preoperative and operative factors except that recent myocardial infarction was more common in smokers. Nonsmokers had greater weight, body mass index (obesity), and ejection fraction. There was no difference in smokers and nonsmokers in mortality or morbidity at the 99% confidence level.

CONCLUSION

We conclude that there is no need to delay CABG for the patients who are smokers.

Disturbed development of the preimplantation embryo in the insulin-dependent diabetic BB/E rat

Although improved regulation of maternal IDDM during pregnancy has resulted in a major fall in the stillbirth rate, the rates for other problems, such as spontaneous preterm labor, fetuses small for gestational age, congenital malformation, and the incidence of large placentas, remain raised. This has suggested the possibility that the damaging effect of conventionally treated but poorly regulated IDDM may operate primarily at the earliest stages of gestation, even before the diagnosis of pregnancy has been made. This study shows that spontaneous autoimmune IDDM in the Bio Breeding/Edinburgh (BB/E) rat is associated with severe disturbance in the development of the preimplantation embryo in a majority of pregnancies, as indicated by a fivefold increase in the incidence of degenerate fragmented embryos and a 33% reduction in the number of expanded blastocysts and in those blastocysts that reach the expanded stage a 20% cellular deficit in the inner-cell mass without any change in trophectoderm cell number. In addition, we find that blastocysts removed from diabetic rats and cultured in vitro for 24 h show no sign of "catch-up" growth of the inner-cell mass, although under these conditions, the trophectoderm exhibits a 25% cellular accretion. It is tempting to speculate that these phenomena are a presage of the characteristic combination of fetal growth retardation and large placentas, which are a feature of both BB/E rat and human IDDM pregnancy.

Prevalence and associations of retinal vein occlusion in Australia. The Blue Mountains Eye Study

OBJECTIVE

To determine the prevalence and associations of retinal vein occlusion (RVO) in a defined older Australian population.

DESIGN

Participants (N = 3654; age, > or = 49 years), representing 88% of the permanent residents from an area west of Sydney, Australia, underwent a detailed eye examination, including stereophotography (Zeiss). The diagnosis of RVO was made clinically and from photographic grading.

RESULTS

Signs of RVO were found in 59 participants (1.6%; 95% confidence interval, 1.3-1.9). The prevalence for each age-specific participant was as follows: 0.7%, younger than 60 years; 1.2%, 60 to 69 years; 2.1%, 70 to 79 years; and 4.6%, 80 years or older. There was no significant sex difference in prevalence. Branch RVO was observed in 41 subjects (69.5%); of this number, 10 subjects had branch RVO outside the vascular arcade or in the nasal fundus and 3 subjects developed new vessels. Hemispheric RVO was found in 3 subjects (5.1%), and central RVO was observed in 15 (25%); RVO was bilateral in 3 subjects (5.1%). Visual acuity was affected most in the people with central RVO, with a visual acuity of 20/200 or less in 60% compared with 14% among the people with branch RVO. Retinal vein occlusion was the fifth most frequent cause of unilateral blindness in this population. Significant associations with RVO were found with glaucoma, hypertension, stroke, and angina.

CONCLUSIONS

This study emphasizes RVO as an important cause of unilateral visual loss in an older population. The proportion of the 3 vein occlusion sites shows some differences from those of clinic-based reports and suggests a likely selection bias in previous clinic studies.

Prevalence of open-angle glaucoma in Australia. The Blue Mountains Eye Study

PURPOSE

The purpose of this study was to determine the prevalence of open-angle glaucoma and ocular hypertension in an Australian community whose residents are 49 years of age or older.

SUBJECTS

There were 3654 persons, representing 82.4% of permanent residents from an area west of Sydney, Australia, who were examined. The population was identified by a door-to-door census of all dwellings and by closely matched findings from the national census.

METHODS

All participants received a detailed eye examination, including applanation tonometry, suprathreshold automated perimetry (Humphrey 76-point test), and Zeiss stereoscopic optic disc photography. Glaucoma suspects were asked to return for full threshold fields (Humphrey 30-2 test), gonioscopy, and repeat tonometry.

RESULTS

A 5-point hemifield difference on the 76-point test was found in 616 persons (19% of people tested). Humphrey 30-2 tests were performed on 336 glaucoma suspects (9.2% of population), of whom 125 had typical glaucomatous field defects. Two hundred three persons had enlarged or asymmetric cup-disc ratios (> or = 0.7 in 1 or both eyes or a cup-disc ratio difference of > or = 0.3). Open-angle glaucoma was diagnosed when glaucomatous defects on the 30-2 test matched the optic disc changes, without regard to the intraocular pressure level. This congruence was found in 87 participants (2.4%), whereas an additional 21 persons (0.6%) had clinical signs of open-angle glaucoma but incomplete examination findings. Open-angle glaucoma was thus found in 108 persons, a prevalence of 3.0% (95% confidence interval [CI], 2.5-3.6), of whom 49% were diagnosed previously. An exponential rise in prevalence was observed with increasing age. Ocular hypertension, defined as an intraocular pressure in either eye greater than 21 mmHg, without matching disc and field changes, was present in 3.7% of this population (95% CI, 3.1-4.3), but there was no significant age-related increase in prevalence. The prevalence of glaucoma was higher in women after adjusting for age (odds ratio, 1.5; CI, 1.0-2.2). There was no sex difference in the age-adjusted prevalence of ocular hypertension.

CONCLUSIONS

These data provide detailed age and sex-specific prevalence rates for open-angle glaucoma and ocular hypertension in an older Australian population.

Pain in pediatric human immunodeficiency virus infection: incidence and characteristics in a single-institution pilot study

OBJECTIVE

Children with human immunodeficiency virus (HIV) infection have multiple complications associated with the disease process. Many of these complications are potentially painful and could affect the patient's quality of life. We examined the incidence and characteristics of the perception of pain in a cohort of families with children with HIV infection.

METHODOLOGY

A questionnaire was developed and validated with a cohort of families with children with cancer. In a survey of families at the Pediatric Branch of the National Cancer Institute, 61 children with HIV infection and their care givers, along with 19 children with cancer and their care givers, were interviewed to determine the incidence and impact of pain.

RESULTS

Fifty-nine percent of the HIV-infected children and 55% of their care givers described pain as a component of their illness that impacted on their lives. Younger children and girls tended to report more pain. There was also a tendency for biological parents to expect and to treat more pain than foster parents, although there was no difference in the incidence of pain that biological and foster parents reported for their children. No differences were found between parents who were HIV positive and those who were not. In addition, no correlations were noted in incidence, expectation, or impact of pain with disease progression or surrogate markers such as CD4 counts. Pain in HIV-infected patients tended to be either in the gastrointestinal tract or limbs and usually responded to nonsteroidal anti-inflammatory therapy. The patients with cancer reported an incidence (47%) and impact of pain similar to those of previously reported studies on pediatric patients with cancer.

CONCLUSION

Pain is common among children infected with HIV and can adversely impact on their lives, and its management should be a component of the general care of these patients.

Epidermal and dermal effects of topical lactic acid

BACKGROUND

Many alpha-hydroxy acid products, containing low- or high-acid concentrations, are being used. It is not known whether different products perform differently or whether they modulate changes in both the epidermis and dermis.

OBJECTIVE

The purpose was to examine whether treatment with 5% and 12% lactic acid produces different cosmetic results and produces changes in the epidermis and dermis.

METHODS

Test participants applied either 5% or 12% lactic acid twice a day for 3 months. Changes in skin smoothness and texture, the depth and number of lines and wrinkles, and epidermal and dermal firmness and thickness were determined.

RESULTS

Treatment with 12% lactic acid resulted in increased epidermal and dermal firmness and thickness and clinical improvement in skin smoothness and in the appearance of lines and wrinkles. No dermal changes were observed after treatment with 5% lactic acid; however, similar clinical and epidermal changes were noted.

CONCLUSION

The results demonstrate that cosmetic benefits from the use of alpha-hydroxy acids are caused by modification of the skin surface, the epidermis and the dermis. Although 5% lactic acid modulates surface and epidermal changes, 12% lactic acid influences both the epidermis and the dermis.

An exact McNemar test for paired binary Markov chains

A straightforward extension of the McNemar test for paired binary data yields an exact test for the equality of the limiting marginal distributions for bivariate binary Markov chains. The exact distribution of the test statistics under the null hypothesis of equal marginals depends on the classical cell occupancy statistics for the Bose-Einstein model. Exact p-values are computed for the one-sided test, and the mean and variance of the test statistic are found. The power of the Markov-McNemar test is found to be close to the power of the classical McNemar test for independent paired observations when the independence assumption holds. The method is applied to the comparison of ribosomal DNA sequences.

Fiber optic pressure sensor for biomedical applications

In vivo measurement of blood pressure is critical in many settings, including patient care, medical research, and control of cardiovascular assist and replacement devices. This article describes a pressure sensor based on fiber optic, white light interferometry. An optical interference filter formed between the end face of an optical fiber and the sensing diaphragm selectively reflects a wavelength component. A low cost, thin film optical wedge interferometer placed at the output end detects the wavelength of the reflected signal, which represents a unique cavity length of the interference filter directly related to the diaphragm deflection and, therefore, pressure. Several key features of this sensing scheme include low drift, high accuracy, and insensitivity to light loss factors along the length of the optical fiber. This fiber optic pressure sensor promises significant advances as a medical monitoring tool, a research instrument, and a component of cardiovascular assist and replacement devices. A prototype pressure gauge has been built, and the feasibility of the optical approach verified. Experimental results of the prototype gauge for resolution, repeatability, and drift and a preliminary design for a high resolution, low drift, miniature fiber optic pressure probe are presented herein.

Molecular dynamics simulations of valinomycin and its potassium complex in homogeneous solvents

Molecular dynamics simulations of kalinomycin (VM) and its potassium complex in water and in a Lennard Jones solvent are reported. In agreement with experimental evidence the structure of K(+)-VM in nonpolar solution is similar to the solid state structure whereas the structure of uncomplexed VM is not. In water uncomplexed VM retains the Lac and HyV faces (which are lost in nonpolar solution) and shows some similarity with the solid-state structure obtained by crystallization from dimethyl sulfoxide (DMSO). However, also in agreement with spectroscopic data a dynamic equilibrium between a set of conformers is established in both solvents. Our model reproduces the experimental dipole moment (3.6 D) of VM in nonpolar solution. We also observed the spontaneous decomplexation of K(+)-VM in water, with the ion passing through the HyV face in preference to the Lac face. Water attack was observed through both faces. The time scale for all conformational transitions is of the order of 100 ps, with structural changes associated with the (de)-complexation reaction controlled by the ring dihedrals in the vicinity of the L-lactic acid residues. Global structural functions, radial distribution functions, and VM ring dihedral analysis are presented, along with an analysis of the decomplexation event.

Client self-determination and professional intervention: striking a balance

Social workers find themselves caught in the cross fire between two imperatives: (1) outcome-oriented and competency-based practice requisites and (2) the principle of client self-determination. In this context, the authors hypothesize that social workers use a wide range of gradations along a continuum of practice directiveness. Furthermore, there is ethical justification for this diverse role repertoire. Directiveness modalities are influenced by specific conditional factors that guide practitioner behavior. A study is described that empirically explores and amplifies these hypotheses.

A pharmacoeconomic study of the management of major depression: patients in a TennCare HMO

The purpose of this study was to evaluate the direct medical costs of treating patients diagnosed with major depression in a TennCare managed care setting. This retrospective analysis was conducted on paid-claims data (including a 10-month lag) from January through December 1994 for patients who met criteria for major depressive disorder and were receiving tricyclic antidepressants (TCAs) or selective serotonin-reuptake inhibitors (SSRIs), for at least three consecutive months. Expenditures measured included office visits, hospital charges, emergency room charges, and drug costs. A total of 976 HMO beneficiaries were identified, and 76 randomly selected patients who were receiving TCAs were compared with 76 randomly selected patients who were receiving SSRIs to evaluate total cost of therapy associated with these two classes of antidepressants. The results of this analysis indicate that the total cost of treatment for Medicaid patients suffering major depression is similar between these two classes of antidepressants. Also, among the three SSRIs, the average daily dose was lowest for paroxetine (21.1 mg/day) and highest with sertraline (81.3 mg/day) and concomitant antidepressant therapy highest with fluoxetine (7.4%).

DL_POLY_2.0: a general-purpose parallel molecular dynamics simulation package

DL_POLY_2.0 is a general-purpose parallel molecular dynamics simulation package developed at Daresbury Laboratory under the auspices of the Council for the Central Laboratory of the Research Councils. Written to support academic research, it has a wide range of applications and is designed to run on a wide range of computers: from single processor workstations to parallel supercomputers. Its structure, functionality, performance, and availability are described.

Tetanus immunity in an older Australian population

OBJECTIVE

To evaluate the effectiveness in older Australians of the current tetanus vaccination program.

DESIGN

A cross-sectional survey of tetanus immunity (enzyme immunoassay of serum samples) in an older population in New South Wales. Self-reported history of tetanus vaccination was compared with serologically measured immunity.

PARTICIPANTS

430 randomly selected adults, 49 years of age and older, from the Blue Mountains Eye Study population.

RESULTS

Fifty-two per cent (95% confidence interval [CI], 47%-57%) of adults 49 years of age and older had protective levels of tetanus antitoxin ( > 0.15 IU/mL). There was a significant decline in the prevalence of immunity with increasing age (chi 2 for linear trend, P = 0.036), and women were less likely to be immune regardless of their age (Mantel-Haenszel weighted odds ratio, 0.65; CI, 0.43-0.92). Thirty-five per cent (95% CI, 31%-40%) of all participants reported that they had been vaccinated in the preceding 10 years. Although self-reported tetanus vaccination history was associated with tetanus immunity, it was neither sensitive nor specific as a test for immunity.

CONCLUSIONS

About half the adults 49 years of age and older in the Blue Mountains area of New South Wales do not have protective levels of tetanus antitoxin because of inadequate vaccination coverage in this age group. Vaccination history is not a reliable indicator of tetanus immunity and a system is needed for accurate recording of adult vaccination.

Magnetic resonance imaging of peripartum rupture of the symphysis pubis

BACKGROUND

Peripartum pubic symphyseal rupture is diagnosed on clinical grounds. Although the diagnosis may be supported by radiography, which shows diastasis of the pubic rami, magnetic resonance imaging (MRI) can visualize the nature of the soft tissue injury.

CASE

Two puerperas thought clinically to have pubic symphyseal rupture were imaged with MRI. In addition to diastasis of the pubic rami, clefts were seen within the symphyseal cartilage, extending the entire breadth of the joint. The clefts were filled with fluid or hemorrhage, seen in T1- and T2-weighted images. The fluid was encapsulated within the joint by the surrounding ligaments. Four control normal puerperas, who had vaginal deliveries but were asymptomatic, showed none of the aforementioned findings.

CONCLUSION

MRI can visualize the soft tissue injury seen in pubic symphyseal rupture and may be used to confirm the clinical diagnosis.

The use of synthetic Cecropin (D5C) in disinfecting contact lens solutions

PURPOSE

Microbial keratitis caused by Pseudomonas aeruginosa is the most common contact lens associated corneal infection. Cecropins are microbicidal peptides isolated from the hemolymph of the Cecropia moth. Previous in vitro studies have demonstrated their efficacy against a broad spectrum of ocular pathogens. This study was designed: a) to evaluate the antimicrobial potency of three different contact lens solutions (Renu, Complete, and Opti-Free) against P. aeruginosa, and b) to evaluate the activity of the same contact lens solutions in combination with a synthetic cecropin analog, D5C, against the challenge organism in the presence of a soft contact lens.

METHODS

A virulent strain of P.aeruginosa isolated from a case of ulcerative keratitis was used in the study. Three different concentrations of bacteria (10(3), 10(5) and 10(7) CFU/mL) were inoculated into the contact lens solutions and into buffered saline, which was employed as a control. The samples were incubated at 27 degrees C, and at time 0, 30, and 90 minutes, 24, 48, and 72 hours, and aliquots of the test solutions were plated and subcultured on nutrient agar. After 24 hours of incubation at 37 degrees C, colonies observed on the nutrient agar plates were counted. To study the antimicrobial efficacy of D5C (100 micrograms/mL), we used the identical test series and assay, adding a soft contact lens to the solutions and a larger inoculum of bacteria (10(9) CFU/mL).

RESULTS

After 72 hours, all of the contact lens solutions tested sterilized 10(3) CFU/mL of P. aeruginosa. At 10(7) CFU/mL, they yielded greater than 2 logs of killing of the bacteria, but the solutions were not sterilized. The addition of D5C (100 micrograms/mL) to the contact lens solutions yielded greater than 3 logs of killing with a larger inoculum of bacteria in the presence of the soft contact lens.

CONCLUSION

The contact lens solutions tested were effective against P. aeruginosa at 27 degrees C for up to 72 hours with an inoculum of 10(3) CFU/mL. The addition of D5C augmented their antimicrobial activity in the presence of the contact lens.

Distribution of alpha 1A, alpha 1B and alpha 1E voltage-dependent calcium channel subunits in the human hippocampus and parahippocampal gyrus

The distribution of voltage-dependent calcium channel subunits in the central nervous system may provide information about the function of these channels. The present study examined the distribution of three alpha-1 subunits, alpha 1A, alpha 1B and alpha 1E, in the normal human hippocampal formation and parahippocampal gyrus using the techniques of in situ hybridization and immunocytochemistry. All three subunit mRNAs appeared to be similarly localized, with high levels of expression in the dentate granule and CA pyramidal layer. At the protein level, alpha 1A, alpha 1B and alpha 1E subunits were differentially localized. In general, alpha 1A-immunoreactivity was most intense in cell bodies and dendritic processes, including dentate granule cells, CA3 pyramidal cells and entorhinal cortex pre-alpha and pri-alpha cells. The alpha 1B antibody exhibited relatively weak staining of cell bodies but stronger staining of neuropil, especially in certain regions of high synaptic density such as the polymorphic layer of the dentate gyrus and the stratum lucidum and radiatum of the CA regions. The alpha 1E staining pattern shared features in common with both alpha 1A and alpha 1B, with strong immunoreactivity in dentate granule, CA3 pyramidal and entorhinal cortex pri-alpha cells, as well as staining of the CA3 stratum lucidum. These findings suggest regions in which particular subunits may be involved in synaptic communication. For example, comparison of alpha 1B and alpha 1E staining in the CA3 stratum lucidum with calbindin-immuno-reactivity suggested that these two calcium channels subunits may be localized presynaptically in mossy fibre terminals and therefore may be involved in neurotransmitter release from these terminals.

Chronic nonpulsatile blood flow. III. Effects of pump flow rate on oxygen transport and utilization in chronic nonpulsatile biventricular bypass

The relationship between blood flow and oxygen transport was studied in five calves with chronic nonpulsatile biventricular bypass. Seven days was allowed for recovery from the effects of anesthesia and operation; the natural heart was then fibrillated. Pump flows were maintained at nominal rates of 90, 100, or 120 ml.kg-1.min for 1 week each, with the sequence varied from experiment to experiment. Venous and arterial blood samples were taken at rest for blood gas analysis. Serum lactate analysis was done twice a week, on the third and seventh days after each pump flow change. Serum catecholamine levels were assayed on the seventh day of each flow rate. Progressive exercise tests were also conducted during each test segment. Basal oxygen consumption of a 4-month-old calf was 6.3 +/- 0.3 ml.kg-1.min-1. The mixed venous oxygen tension decreased when pump flow rate was reduced (29.6 +/- 1.0, 28.3 +/- 1.2, and 23.8 +/- 0.9 mm Hg at 120, 100, and 90 ml.kg-1.min-1 of pump flow, respectively), and oxygen extraction increased linearly when pump flow rate was reduced. Hemoglobin concentration significantly affected oxygen extraction rate. Serum lactate concentration increased significantly at a 90 ml.kg-1.min-1 perfusion compared with concentrations at other pump flow rates (7.81 +/- 2.42 mEq/L at 90 ml.kg-1.min-1 vs 0.71 +/- 0.19 and 0.73 +/- 0.81 mEq/L at 100 and 120 ml.kg-1.min-1, respectively; p < 0.01, analysis of variance, Scheffe F test). Maximum oxygen extraction during exercise was 78%. These results suggest that a critical flow level between 90 and 100 ml.kg-1.min-1 maintains oxidative metabolism in the calf with chronic nonpulsatile flow. The resulting oxygen delivery was slightly higher than that indicated in the literature. Maximal oxygen extraction was normal.