Somatic Support with Veno-venous ECMO in a Pregnant Woman with Brain Death: A Case Report

Supporting homeostasis in a pregnant woman with brain death to achieve fetal viability is called somatic support. We present a case of young pregnant woman at 21 weeks' gestation who developed acute respiratory distress syndrome secondary to influenza A H2N3 infection requiring veno-venous extracorporeal membrane oxygenation (VV ECMO) support for refractory hypoxemia. The clinical course was complicated by intracranial hemorrhage and subsequent brain death. After multidisciplinary team discussion with her family, consensus was reached to continue somatic support with VV ECMO to enable fetal development to attain extrauterine viability. The challenging clinical, ethical, and legal concerns are discussed.

Implication of coughing dynamics on safe social distancing in an indoor environment-A numerical perspective

Coughing is a primary symptomatic pathway of respiratory or air-borne disease transmission, including COVID-19. Several parameters such as cougher's age, gender, and posture affect particle dispersion indoors. This study numerically investigates the transient cough evolution, contamination range, particle reach probability, and deposition fraction for different age groups of males and females in standing and sitting postures in a ventilated room. The efficacy of a cloth mask has also been studied with and without the influence of air ventilation. Validated Computational Fluid Dynamics methodology has been implemented to model complex physics such as turbulent buoyant cloud, particle-air interaction, particle collision/breakup, and droplet evaporation. Our results show that overall, the contamination range is slightly lower for females due to lower cough velocities and particle counts. Moreover, a significant fraction of particles crosses the two meters social distancing guideline threshold with an unhindered cough. Besides, wearing a cloth mask reduces the average contamination range by approximately two-third of the distance compared to coughing without the mask. However, aerosolized particles reach longer streamwise distances and drift for extended durations beyond thirty seconds. This study can be used to improve the heating, ventilation, and air conditioning recommendations and distancing guidelines in indoor settings.

Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model

Purpose

Steroid-induced glaucoma is a common form of secondary open angle glaucoma characterized by ocular hypertension (elevated intraocular pressure [IOP]) in response to prolonged glucocorticoid exposure. Elevated IOP occurs with increased outflow resistance and altered trabecular meshwork (TM) function. Recently, we used an optogenetic approach in TM to regulate the 5-phosphatase, OCRL, which contributes to regulating PI(4,5)P2 levels. Here, we applied this system with the aim of reversing compromised outflow function in a steroid-induced ocular hypertension mouse model.

Methods

Elevated IOP was induced by chronic subconjunctival dexamethasone injections in wild-type C57Bl/6j mice. AAV2 viruses containing optogenetic modules of cryptochrome 2 (Cry2)-OCRL-5ptase and CIBN-GFP were injected into the anterior chamber. Four weeks after viral expression and dexamethasone exposure, IOP was measured by tonometer and outflow facility was measured by perfusion apparatus. Human TM cells were treated with dexamethasone, stimulated by light and treated with rhodamine-phalloidin to analyze actin structure.

Results

Dexamethasone treatment elevated IOP and decreased outflow facility in wild-type mice. Optogenetic constructs were expressed in the TM of mouse eyes. Light stimulation caused CRY2-OCRL-5ptase to translocate to plasma membrane (CIBN-CAAX-GFP) and cilia (CIBN-SSTR3-GFP) in TM cells, which rescued the IOP and outflow facility. In addition, aberrant actin structures formed by dexamethasone treatment were reduced by optogenetic stimulation in human TM cells in culture.

Conclusions

Subcellular targeting of inositol phosphatases to remove PIP2 represents a promising strategy to reverse defective TM function in steroid-induced ocular hypertension.

Translational Relevance

Targeted modulation of OCRL may be used to decrease steroid-induced elevated IOP.

Examining metastatic behavior within 3D bioprinted vasculature for the validation of a 3D computational flow model

Understanding the dynamics of circulating tumor cell (CTC) behavior within the vasculature has remained an elusive goal in cancer biology. To elucidate the contribution of hydrodynamics in determining sites of CTC vascular colonization, the physical forces affecting these cells must be evaluated in a highly controlled manner. To this end, we have bioprinted endothelialized vascular beds and perfused these constructs with metastatic mammary gland cells under physiological flow rates. By pairing these in vitro devices with an advanced computational flow model, we found that the bioprinted analog was readily capable of evaluating the accuracy and integrated complexity of a computational flow model, while also highlighting the discrete contribution of hydrodynamics in vascular colonization. This intersection of these two technologies, bioprinting and computational simulation, is a key demonstration in the establishment of an experimentation pipeline for the understanding of complex biophysical events.

Environmental Exposure of Children to Toxic Trace Elements (Hg, Cr, As) in an Urban Area of Yucatan, Mexico: Water, Blood, and Urine Levels

Merida is the largest urban center in the Mexican State of Yucatan. Here domestic sewage is deposited in poorly built septic tanks and is not adequately treated. Because of contamination from such waste, water from the top 20 m of the aquifer is unsuitable for human consumption. Given this situation and because children are highly vulnerable to environmental pollution, including exposure to toxic trace elements, this study focused on evaluating the exposure of children to arsenic (As), chromium (Cr), and mercury (Hg) in water. It also evaluated the relationship between the levels of these elements in water and their concentrations in urine and blood. Among the 33 children monitored in the study, arsenic surpassed WHO limits for blood in 37% of the cases, which could result from the ingestion of poultry contaminated with organoarsenic compounds. In the case of WHO limits for Mercury, 65% of the water samples analyzed, 28% of urine samples, and 12% of blood samples exceeded them. Mercury exposure was correlated with biological sex, some lifestyle factors, and the zone in Merida in which children live. These data suggest that the levels of some toxic metals in children may be affected by water source, socioeconomic factors, and individual behavior.

Water Consumption as Source of Arsenic, Chromium, and Mercury in Children Living in Rural Yucatan, Mexico: Blood and Urine Levels

Studies investigating the correlation between metal content in water and metal levels in children are scarce worldwide, but especially in developing nations. Therefore, this study investigates the correlation between arsenic, chromium, and mercury concentrations in drinking and cooking water and in blood and urine samples collected from healthy and supposedly non-exposed children from a rural area in Yucatan, Mexico. Mercury in water shows concentrations above the recommended World Health Organization (WHO) value for drinking and cooking water. Also, 25% of the children show mercury in urine above the WHO recommended value. Multivariate analyses show a significant role for drinking and cooking water as a vector of exposure in children. Also, the factor analysis shows chronic exposure in the case of arsenic, as well as an ongoing detoxification process through urine in the case of mercury. Further studies should be done in order to determine other potential metal exposure pathways among children.

Delphinol® standardized maqui berry extract significantly lowers blood glucose and improves blood lipid profile in prediabetic individuals in three-month clinical trial

BACKGROUND

Previous research has suggested that supplementation with delphinidin-rich maqui berry extract Delphinol® significantly alters postprandial carbohydrate metabolism and acutely lowers both insulin and glucose at fasting conditions. Additionally, the maqui berry extract affects absorption of glucose, which was attributed by other groups to SGLT1-inhibition.

METHODS

Because this activity profile suggests promising potential for improving glucose metabolism in prediabetes, we investigated in a three months trial the effects of Delphinol® in 31 subjects, presenting just diagnose, moderate glucose intolerance, measuring HbA1c, glucose tolerance and lipid profile in monthly intervals.

RESULTS

Average levels of glycosylated hemoglobin decreased from initial 5.65±0.09% (SE) to 5.50±0.08% (SE) (P=0.084) after one month, 5.39±0.08% (SE) (P=0.010) after two months and 5.35±0.08% (SE) (P=0.003) after three months of daily supplementation with 180 mg Delphinol® in the morning. Fasting insulin and glucose were non-significantly lowered. Oral Glucose Tolerance Test (OGTT) performed in monthly intervals did not result in significant alterations compared to baseline characteristics. Blood lipid measurements showed significant reduction of LDL after three months (P=0.001), VLDL already decrease after one month (P=0.019). VLDL values subsequently raise again showing no statistical difference with the starting condition. HDL increased significantly over baseline during the entire treatment period. Total cholesterol and triglycerides did not present with significant changes.

CONCLUSIONS

Our findings point to considerable health potentials benefits of Delphinol, particularly related to the improvement of glucose metabolism. Delphinol® was well tolerated and no adverse effects occurred.

Simple lines and shapes are associated with, and communicate, distinct emotions

We investigated whether lines and shapes that present face-like features would be associated with emotions. In Experiment 1, participants associated concave, convex, or straight lines with the words happy or sad. Participants found it easiest to associate the concave line with happy and the convex line with sad. In Experiment 2, participants rated (valence, pleasantness, liking, and tension) and categorised (valence and emotion words) two convex and concave lines that were paired with six distinct pairs of eyes. The presence of eyes affected participants' valence ratings and response latencies; more congruent eye-mouth matches produced more consistent ratings and faster reaction times. In Experiment 3, we examined whether dots that resembled eyes would be associated with emotional words. Participants found it easier to match certain sets of dots with specific emotions. These results suggest that facial gestures that are associated with specific emotions can be captured using relatively simple shapes and lines.

Inherently unstable networks collapse to a critical point

Nonequilibrium systems that are driven or drive themselves towards a critical point have been studied for almost three decades. Here we present a minimalist example of such a system, motivated by experiments on collapsing active elastic networks. Our model of an unstable elastic network exhibits a collapse towards a critical point from any macroscopically connected initial configuration. Taking into account steric interactions within the network, the model qualitatively and quantitatively reproduces results of the experiments on collapsing active gels.

Anomalous discontinuity at the percolation critical point of active gels

We develop a percolation model motivated by recent experimental studies of gels with active network remodeling by molecular motors. This remodeling was found to lead to a critical state reminiscent of random percolation (RP), but with a cluster distribution inconsistent with RP. Our model not only can account for these experiments, but also exhibits an unusual type of mixed phase transition: We find that the transition is characterized by signatures of criticality, but with a discontinuity in the order parameter.

Achieving the Great Lakes Initiative mercury limits in oil refinery effluent

To meet the stringent Great Lakes Initiative (GLI) wastewater discharge mercury (Hg) limit of 1.3 ppt (ng/L), mercury removal technologies need to be identified and investigated. The goals of this study were to (1) identify and assess available wastewater treatment technologies for mercury removal from an oil refinery wastewater; and (2) conduct bench-scale tests to provide comparable, transparent, and uniform results to assess their performance at low mercury concentrations. The study found that many tested technologies were able to achieve the GLI mercury target concentration at the bench-scale, albeit with different efficiencies and engineering implications. These results demonstrate that at this scale there is no fundamental physical or chemical barrier to achieving < 1.3 ng Hg/L in the tested wastewater. The study also found that some technologies were effective on particulate mercury whereas others were effective on dissolved mercury. One emerging treatment technology was found to be effective on both particulate and dissolved mercury. Three mercury-removal technologies--ultrafiltration (particulate mercury), adsorption (dissolved mercury), and an emerging reactive filtration technology (particulate and dissolved mercury)--are recommended for further study. This research offers treatment alternatives for different forms of mercury in an oil refinery wastewater, which might be applicable to other types of mercury-containing wastewater.

Improving data quality on low level mercury wastewater analysis

In order to compare treatability test results evaluating low-level mercury (Hg) removal from oil refinery wastewater, improvements in Hg analytical methods were conducted at two US EPA certified analytical labs. The revisions in the analytical protocols improved Hg recoveries and hence enabled more reliable data interpretation and comparison for the specific wastewater tested. Nevertheless, significant differences between results from the two laboratories were identified in a split-sample experiment.

A study of nanomaterial dispersion in solution by wet-cell transmission electron microscopy

Preparation of nanomaterial dispersion or nanofluids requires good characterization techniques, including particle size and morphological measurements. A reliable and straight-forward process to characterize and quantify the degree of dispersion and agglomeration is needed. A wet-cell transmission electron microscope (TEM) technique has been developed to make comparisons between sonicated and hand-shaken solutions of both aluminum oxide nanoparticles and multi-walled carbon nanotubes. In each case, the wet-cell TEM technique reveals images of nanoparticles well dispersed in aqueous solutions due in part to the use of ultrasonic power instead of simply manual shaking and stirring. The technique is currently qualitative and shows great potential for a host of nanotechnology applications.

Applying the concept of metamorphosis to the crustose-to-erect thallus transition of macroalgae

Metamorphosis is broadly defined as a more or less radical morphological change between 2 multicellular life stages within an organism's life phase, often marking the transition from pre-reproductive to reproductive stages. It involves structural reorganization and major physiological changes, generally under the control of endogenous and exogenous factors and often resulting in changes in habitat use. This concept has been applied to the crustose-to-erect thallus transition of some red algae and the present study evaluates the validity of such hypotheses. Available literature suggests that the crustose-to-erect thallus transition involves significant morphological and habitat changes, separating pre-reproductive and reproductive stages. The onset of the morphological changes (for example axis differentiation) appears regulated by endogenous signals (growth factors) and growth is modified by environmental factors. The algae do not exhibit structural reorganization, however, probably due to their simple morphological structure and the lack of several cell and tissue mechanisms involving cell motility. The presence of cell walls in the algae impairs cell motility and maintains the cell in a fixed position within the plant. These are important differences restricting the extension of the definition of metamorphosis to the crust-to-erect thallus transition. The above restrictions also seem to apply to other macroalgae, fungi, and terrestrial plants.

An unusual presentation of chest pain

Cardiac disease is common among patients with Systemic Lupus Erythematosus (SLE). Pericardial, myocardial, valvular, and coronary artery involvement have been extensively reported. The three major coronary abnormalities associated with myocardial injury in SLE are premature atherosclerosis, coronary arteritis and, less frequently, coronary aneurysms. A 26-year-old black male patient with a 5-year history of anti-phospholipid syndrome sustained a lateral wall myocardial infarct associated to angiographic evidences of multiple, diffuse, saccular coronary aneurysms without evidence of atherosclerotic occlusive disease in all three coronary arteries. Serologic studies were consistent with active SLE. Lupus-associated nephritis was also present. Radiographic studies showed no evidence of brain or thoracic aneurysms. A transthoracic echocardiogram showed an estimated ejection fraction of 35% and a moderate pericardial effusion. High dose i.v. steroids were started along with systemic anticoagulation. The patient had an uneventful clinical course and was discharged by the fourteenth day on high doses of oral steroids (60 mg daily), statins, oral anticoagulation (warfarin 5 mg), antihypertensives and aspirin. The patient was lost to follow-up and developed steroid-induced hyperglycemia, 20 pound weight gain and warfarin intoxication. A three-month follow up coronary angiography showed complete resolution of the aneurysms and serologic studies showed no active autoimmune disorder at that time. Coronary artery aneurysms have previously been reported in 15 cases of patients with SLE. An extensive Medline search of the literature revealed no previous reports of diffuse saccular coronary aneurysms involving all three coronary arteries associated with active SLE. This case highlights the unusual presentation of acute SLE in a young patient complicated by multiple aneurysms and acute myocardial infarction. In this case, we believe that a direct causal association exists between acute SLE-associated aneurysms and myocardial ischemic injury. Early recognition and prompt treatment with large doses of corticosteroids may decrease the mortality and morbidity associated with this condition.

[Hypothalamic hamartoma causing precocious puberty: A case report]

Hypothalamic hamartomas are non neoplastic lesions that may cause precocious puberty with or without complex seizures, personality disorders and mental retardation. We report a 14 years old male that had a precocious puberty at the age of 11 and a prolonged episode of altered sensorium with automatism, that was diagnosed as a complex seizure. Physical examination showed a sexual development classified as Tanner stage III-IV, a height of 168 cm and a weight of 61 kg. Neurological examination was normal. A CAT scan showed a 13 x 13 x 9 mm mass in the suprasellar cistern, between the infundibulum and the brain stem, without exerting a mass effect over adjacent structures. It was diagnosed as an hypothalamic hamartoma.

Effect of dietary oils, cholesterol and antioxidant vitamin supplementation on liver microsomal fluidity and xenobiotic-metabolizing enzymes in rats

This study was undertaken to compare the effects of four oils: corn (C), olive (O), hazelnut (H) or fish (F), and the intake of two supplements: cholesterol, 1% (Ch) or dl-alpha-tocopherol acetate, 500 mg/kg, and beta-carotene, 30 mg/kg (V), on liver microsomal fluidity, cyt P450 content and aniline hydroxylase (AH), aminopyrine-N-dimethylase (AND) and UDP-glucuronyltransferase (UDP-GT) activities. Male Sprague-Dawley rats (n = 6/group) were fed semipurified diets containing 15% oil, without or with Ch or V, for 20 days. Dietary intake and feed efficiency were lower in rats fed F. Relative liver weight was higher in animals fed F, similar in O and H, and lower in the group fed C. The intake of V increased feed intake in C+V group and decreased the relative liver weight of F+V group, which also decreased with the intake of F+Ch. Ch intake increased the relative liver weight in all groups consuming vegetable oils. Cyt P450 content was higher in rats fed F. Decreased cyt P450 content was observed in C+Ch and F+Ch groups, while it augmented in H+Ch group. Mixture V increased cyt P450 in rats fed C+V, F+V and O+V. The highest membrane fluidity was observed in rats fed F. Fluidity was also higher in group H versus O or C. The intake of Ch decreased microsomal fluidity in all groups, while V induced an increase in microsomal fluidity in group O+V. Rats fed F exhibited higher enzyme activities. AND activity increased with V only in rats fed H+V, while AH activity increased with V intake in groups F+V and O+V. In the C+V group, fluidity was not affected by V, while the cyt P450 content and UDP-GT activity increased. The O+V group exhibited lower UDP-GT activity and higher fluidity and cyt P450 content. The activity of AH decreased in groups F+Ch and C+Ch. UDP-GT activity was higher in rats fed F. It diminished after the intake of Ch in H+Ch and F+Ch. These results indicate that although AH and AND act in the same microsomal metabolic pathway, their localization into the membrane may be determinant of their activity and the response to dietary lipids. It is shown that F intake exerts the most significant effects upon liver microsomal properties, e.g. higher fluidity, cyt P450 content and enzymatic activities, an effect that prevails over the intake of the supplements tested.

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela: present situation of human and canine infections

The report of a new autochthonous case of human American Visceral Leishmaniasis (AVL) in 1992 in the village of Guayabita, Aragua State, Venezuela (10 degrees 16'N, 67 degrees 28'W; 500 m asl), led us to undertake an epidemiological study in this locality. A demographic survey was conducted using a structured questionnaire in which data was collected regarding sex, age, occupation, length of residence in the area and migratory history. A leishmanin skin test (LST) was applied and samples of venous blood for counter immunoelectrophoresis (CIEP) and immunofluorescent antibodies (IFAT) tests were drawn. The prevalence of positive LST was 11.4%. The positivity was highest among males and increased with age. Young males seemed to be more exposed to infection than females. Since occupation per se did not seem to account for this association, it may be explained as a gender-associated behavior, leading to different degrees of exposure to sand flies. The canine population was also screened for leishmanial infection. One dog was shown to be parasitologically infected with Leishmania sp. Four out of 71 dogs (5.6%) were positive for FG, CIEP, IFAT and Western Blot and 11 (15.5%) were positive for CIEP. These results suggest that after almost 30 years of epidemiological silence, American visceral leishmaniasis has re-emerged in this focus.

Two distinct oncornaviruses harbor an intracytoplasmic tyrosine-based basolateral targeting signal in their viral envelope glycoprotein

It has been clearly established that the budding of the human immunodeficiency virus (HIV-1), a lentivirus, occurs specifically through the basolateral membrane in polarized epithelial cells. More recently, the signal was assigned to a tyrosine-based motif located in the intracytoplasmic domain of the envelope glycoprotein, as previously observed on various other viral and cellular basolateral proteins. In the present study, expression of human T-cell leukemia virus type 1 (HTLV-1) or Moloney murine leukemia virus envelope glycoproteins was used for trans-complementation of an envelope-negative HIV-1. This demonstrated the potential of oncornaviral retrovirus envelope glycoproteins to confer polarized basolateral budding in epithelial Madin-Darby canine kidney cells (MDCK cells). Site-directed mutagenesis confirmed the importance of a common motif encompassing at least one crucial membrane-proximal intracytoplasmic tyrosine residue. The conservation of a similar basolateral maturation signal in different retroviruses further supports its importance in the biology of this group of viruses.

The cellular basis of aqueous outflow regulation

This review begins with an introduction to the concept of the cellular regulation of aqueous outflow, current methods used for its study, and the cell types that are known to participate in this process. Current research in the field is divided into work on cell properties, cell products and extracellular matrix, cytoskeletal and structural changes, and drug interactions.

Improvement of functional magnetic resonance images by pretreatment of data

Functional magnetic resonance images of the brains of subjects performing the finger-tapping paradigm were made using a conventional technique. Two threshold values for the pixels were obtained by analysing pixel by pixel the distributions of the means and variances of each subject's images for 20 consecutive scans, both while performing the task and while at rest. Considerable signal improvement in the final images was achieved by removing from our data all pixels beyond these threshold values (mean < or = 16 and variance > or = 7).

Clinical experience with the long-term use of 1% apraclonidine. Incidence of allergic reactions

OBJECTIVE

To identify the incidence and characteristics of allergic reactions associated with the long-term use of 1% apraclonidine hydrochloride.

METHODS

We undertook a retrospective analysis of 64 patients receiving long-term 1% apraclonidine therapy at the University of California-San Francisco Glaucoma Service. Patients were excluded if the duration of treatment was less than 2 weeks. Demographic data, initial intraocular pressure response, and incidence and characteristics of allergic reactions were obtained through chart review. Student's t test and chi 2 analysis were used to analyze the demographic data, and Kaplan-Meier survival analysis was used to estimate the long-term incidence of local reactions.

RESULTS

Sixty-four patients met the criteria for the study. Of these, 31 (48%) developed an allergic reaction (responders) that led to discontinuation of treatment with the medication, with a mean latency of 4.7 months. Mean follow-up was 13.3 months. Patients free of local reactions (nonresponders) for at least 10 months were able to successfully continue apraclonidine use. Responders tended to be older and female.

CONCLUSIONS

Our data are specific for the 1% preparation; however, physicians prescribing apraclonidine on a long-term basis should be aware of possible allergic reactions. A substantial percentage of patients developed this side effect, but most tolerated the medication for up to 4 months, and those without a local reaction after 10 months appeared to be able to continue apraclonidine use indefinitely. This allergic reaction is likely related to the adrenergic agent itself, and not to preservatives.

Determination of Cd, Cr, Cu, Pb and Zn in human semen by graphite furnace atomic absorption spectrometry after microwave sample dissolution

Human semen samples were analyzed by graphite furnace atomic absorption spectrometry, using L'vov platforms and the method of standard additions, to determine their Cd, Cr, Cu, Pb and Zn content. The samples were analyzed directly and after conventional and microwave wet acid dissolution. Matrix modification, using magnesium and palladium nitrates and ammonium biphosphate solutions, was evaluated for the analysis of the microwave-digested samples. The best results were obtained for Cr, Cu and Zn using Pd(NO3)2, and a mixture of Mg(NO3)2 and Pd(NO3)2 solutions. The direct analysis of water-diluted semen produced inaccurate results with unacceptably high standard deviations. The results obtained for the microwave-dissolved samples showed relative standard deviation values within the range 0.63-8.4%. The analysis of spiked semen solutions showed recoveries of the added analytes ranging from 96 to 104%. The accuracy of the measurements was checked against the NIST 1,577a, bovine liver, standard reference material. Sample dissolution time was drastically reduced from 3-4 hours, using the conventional method, to approximately 8 minutes using the microwave-assisted wet acid digestion procedure.

[The development of the anti-phospholipase A2 antibody response in horses inoculated with venom for the production of polyvalent antisnake serum in Costa Rica]

The development of antibody response against phospholipase A2 activity of Bothrops asper venom was studied in a group of adult and healthy horses used in the production of the polyvalent antivenom at the Instituto Clodomiro Picado. Simultaneously, the general condition of the animals during the immunization schedule was also studied. There was a great individual variability in the immune response, although most of the horses studied reached the highest neutralizing titer after injection of doses of venom of 30 mg and 50 mg. On the other hand, in horses that had been previously immunized and were infected for a second immunization, the highest antibody titer was observed 16-22 days after inoculation. There were only mild alterations in the general condition of the horses as a consequence of venom inoculation. However, local abscesses, fistulae and fibrosis were observed at the site of venom injection. On the basis of the conspicuous individual variability observed, it is proposed that the immune response in horses used in the production of antivenom must be evaluated on individual basis, instead of working with pools of serum samples.

Effects of betaxolol/timolol on epinephrine stimulated cyclic-AMP levels in human trabecular meshwork cells

The effects of timolol and betaxolol were compared for blocking beta agonist stimulation of cyclic-AMP in cultured human trabecular meshwork cells. Epinephrine (10(-5) M) produced a large and rapid increase in HTM cyclic-AMP; timolol (10(-6) M), at concentrations readily achieved in the aqueous humor after 0.5% eyedrops, completely blocked this effect. Recovery from timolol treatment appeared to be relatively slow, with only a 30-40% recovery observed by 9 hours. In comparison, betaxolol (10(-6) M) produced a smaller blockade of the epinephrine effects; a rapid recovery from the betaxolol effects was observed, with a greater than half-maximal response to epinephrine observed 15 minutes after removal of this beta blocker. These findings may help to explain the clinical observations of an outflow facility effect of epinephrine when used in combination protocols with betaxolol, but not with timolol.

Characterization of beta-adrenergic receptors in cultured human trabecular cells and in human trabecular meshwork

The characterization of beta-adrenergic receptors on cultured human trabecular cells and trabecular meshwork from human autopsy eyes was carried out by radioligand binding utilizing (125I)-iodopindolol. In cultured cells, the observed binding of (125I)-iodopindolol was of high affinity (Kd = 43 pM) and saturable. Scatchard plots were linear and revealed a Bmax of 33 +/- 7 fmol/mg of protein. Competition studies with a series of agonists and antagonists revealed that human trabecular cells contain a single class of beta-adrenergic receptors of the beta 2 subtype. Similarly, the IC50 of ICI 89,406 (176 nM) in human trabecular meshwork from autopsy eyes supports the presence of beta 2-adrenergic receptors in this tissue.

Use of immunotoxin to inhibit proliferating human corneal endothelium

Transferrin plays a central role in cellular proliferation and proliferating cells have been shown to express transferrin receptors with increased density. We examined the effect of an immunotoxin consisting of anti-transferrin receptor monoclonal antibody (454A12) conjugated to recombinant ricin A chain (rRTA) on the proliferation of human corneal endothelium (HCE) in vitro. In proliferating cultures an immunotoxin (454A12-rRTA) concentration of 50 ng/mL reduced cell counts at day 7 by at least 89%, with no effect observed at 0.01 ng/ml. In contrast, cell counts were only minimally reduced in confluent cultures, even after 7 days' exposure to high concentrations of immunotoxin. These data suggest that 454A12-rRTA may be used to prevent growth of human corneal endothelium in pathological conditions such as the iridocorneal endothelial (ICE) syndrome.

The cytoskeleton of the cultured human trabecular cell. Characterization and drug responses

To determine the organization of the three major cytoskeletal elements of cultured human trabecular meshwork cells (actin filaments, microtubules and intermediate filaments), we employed fluorescence microscopy and stereo-transmission electron microscopy of extracted, S-1 labeled and critical-point dried cells. Morphologic changes resulting from treatment with cytochalasin B, colchicine, taxol and nocodozole were also characterized. Compared with the cynomolgus monkey trabecular cell, morphologic differences in overall cell shape and orientation of both actin filaments and microtubules were noted. However, the responses to cytoskeletal active drugs were quite similar. Taxol, nocodozole and colchicine had a marked effect on microtubule organization, while nocodozole and colchicine had a marked effect on vimentin filament organization. None of these drugs produced marked changes in human trabecular cell shape. In contrast, treatment with the anti-actin drug cytochalasin B resulted in both a marked change in cell shape associated with organizational changes in all three cytoskeletal elements. These studies suggest a central role of actin filaments in determining overall cell shape and cytoskeletal organization in the cultured human trabecular cell.

Subconjunctival injections. Preservative-related changes in the corneal endothelium

The morphologic effects on rabbit corneal endothelium of several common ophthalmic vehicle constituents were examined following subconjunctival administration. Profound dose-dependent changes consisting of intercellular vacuolization and thickening of the endothelial layer were noted within 1 day following administration of solutions that contained sodium bisulfite or methylparaben and propylparaben. These changes persisted for at least 5 days except in those eyes treated with the lowest concentration of sodium bisulfite. In contrast, administration of sodium citrate and creatinine or unpreserved normal saline resulted in only minimal effects. These changes are of concern because these agents are present in many preparations used to treat a wide variety of eye diseases.

Prenatal and postnatal growth of the human Descemet's membrane

The origin, growth in thickness, and differentiation of Descemet's membrane was studied by light, electron microscopic, morphometric, and statistical methods in 67 specimens from 12 weeks of gestation to 98 years. Descemet's membrane is formed by three major processes: growth in thickness during the prenatal period, prenatal differentiation into a striated basement membrane, and growth in thickness during the postnatal period. The initial step is the synthesis of an ordinary basement membrane, which is very thin and quite different in appearance from the adult Descemet's membrane. Growth of the prenatal Descemet's membrane then proceeds by deposition of a series of similar "membrane units," which are stacked to form a lamellar structure consisting of at least 30 layers by the end of gestation. Second, during prenatal life, differentiation of the membrane leads to the formation of a striated structure through the gradual addition of short and thin cross-linking bridges separated by 110-nm intervals that are disposed in a plane perpendicular to the lamellae. The third process occurs in postnatal life when the membrane continues to grow in thickness by deposition of a nonstriated, nonlamellar material posterior to the striated prenatal layer. Regression analysis suggests that prenatal growth proceeds at a rapid but variable rate best described by a "sigmoid-like" function of age. Postnatal growth, in contrast, proceeds in a predominantly exponential manner but at a slower pace than in the prenatal period. The low variability and large size of our set of measurements make these data especially useful for comparisons with pathologic specimens.