Capillary Membrane Research Articles

Wettability Studies of Capillary PTFE Membranes Applied for Membrane Distillation.

In the present study, the membrane distillation (MD) process was studied with the use of commercial polytetrafluoroethylene (PTFE) capillary membranes. For this purpose, both solutions with NaCl concentrations up to 300 g/L and brines contaminated with oil (70-120 mg/L) were used as feeds. The membrane's wetting resistance was tested by conducting long-term experiments for over 3500 h. Using detailed studies, it has been shown that increasing the salt concentration from 35 to 300 g/L resulted in a 50% reduction in the permeate flux. Nevertheless, the membranes retained 100% of the salt rejection after 2000 h of the module's operation. Moreover, it has been found that performing the MD process with brines contaminated with oil (120 mg/L) led to the wetting of some membranes pores, which it turn resulted in an increase in the distillate's conductivity to 450 µS/cm after 700 h running the process. The mechanism of pore wetting by oil droplets adsorbed on the membrane's surface was presented. Finally, the proposed method of membrane cleaning with the use of a solvent allowed restoring the initial MD module's performance. Consequently, both the permeate flux and distillate conductivity were stable during the MD of the feed containing 35 g/L of NaCl over the next 280 h.

Tissue distribution of ethanol after intraprostatic injection using a porous needle.

To develop a safe and precise method for intraprostatic injection, and to establish correlation between the volume of ethanol injectate and the volume of subsequent infiltrated prostate tissue. We performed intraprostatic injection of 96% ethanol using a needle which has a segment of its wall made of capillary membrane with hundreds of pores in an acute and chronic canine experiment, in heart-beating cadaveric organ donors, and in a xenograft model of human prostate cancer. Whole mount tissue sections were used for three-dimensional reconstruction of the necrotic lesions and calculation of their volumes. The ethanol injection resulted in oval shaped lesions of well-delineated coagulative necrosis. In both healthy human and canine prostates, the prostatic pseudocapsule and neurovascular bundle remained intact without evidence of disruption. There was a linear correlation between administered volume of ethanol and the volume of necrotic lesion. Regression analysis showed strong correlation in the acute canine experiments and in experiments performed on xenografts of human prostate cancer. A formula was calculated for each experiment to estimate the relationship between the injected volume and the volume of infiltrated prostate tissue area. Intraprostatic injection using a porous needle allows for effective and predictable tissue distribution of the injectate in the prostate. Through varying the volume of the agent injected and use of needles with a different length of the porous segment, the volume of infiltrated tissue could be adjusted allowing for targeted focal treatment.

A pilot study of diabetic retinopathy in a porcine model of maturity onset diabetes of the young type 3 (MODY3)

Diabetic retinopathy (DR) is a leading cause of blindness in the working population. Because novel therapeutic intervention require testing, there is an urgent need for reliable animal models that faithfully replicate DR. Pig eyes have many similarities to human eyes anatomically and physiologically. Thus, attempts have been made to establish porcine models of DR by surgical, pharmaceutical or genetical induction of insulin deficiency, and dietary intervention. A previous study reported a transgenic pig model of maturity onset diabetes of the young type 3 (MODY3) developed signs of severe DR such as hemorrhage and proliferative tissue at the surface of the retina. However, the course of development of DR has not been studied in detail in this model. The purpose of this study was to investigate the early phase of DR in a MODY3. MODY3 and wild-type (WT) pigs underwent fundus photography and fluorescein angiogram (FA) before they developed cataracts. Animals were euthanized at age 1, 4, 7, and 10 months. Whole-mount retina and 10-μm thick paraffinized sections were stained with isolectin B4, and vessel density was determined by MATLAB software. At 4 and 7 months, retinal arterioles were immediately cannulated, and vasomotor action was measured by incubation with bradykinin and sodium nitroprusside. In the MODY3 pigs, fasting blood sugar levels gradually increased up to 500 mg/dL. Vascular tortuosity and yellowish spindle-shaped lesions were confirmed in MODY3 pigs at the age of 7 months; however, no microaneurysms were detected on FA. Compared with age-matched WT pigs, MODY3 pigs showed a significant decrease in blood vessel density in the intermediate and deep vascular plexus at 4 and 7 months of age and a slight decrease in capillary density in the superficial vascular plexus at 7 months of age. In MODY3 pigs, electron microscopy revealed thickening of the capillary basement membrane and leukostasis in the major blood vessels at 10 months of age. Bradykinin-induced dilation of retinal arterioles was diminished in MODY3 pigs as early as 7 months of age. Within 1 year after birth, MODY3 pigs show all typical early vascular lesions of diabetes except for microaneurysm formation. This pilot study suggests that the MODY3 pigs may serve as a suitable DR model to test effects of newly developed compounds on DR.

The lymphatic drainage systems in the brain: a novel target for ischemic stroke?

Recent studies have proposed three lymphatic drainage systems in the brain, that is, the glymphatic system, the intramural periarterial drainage pathway, and meningeal lymphatic vessels, whose roles in various neurological diseases have been widely explored. The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid. The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media. Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses. After ischemic stroke, impairment of these systems could lead to cerebral edema, accumulation of toxic factors, and activation of neuroinflammation, while restoration of their normal functions can improve neurological outcomes. In this review, we summarize the basic concepts of these drainage systems, including drainage routes, physiological functions, regulatory mechanisms, and detection technologies. We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke, as well as recent advances in therapeutic strategies targeting these drainage systems. These findings provide information for potential novel strategies for treatment of stroke.

A Comprehensive Review of Diabetic Retinopathy and Diabetic Macular Edema from an Ayurveda Point of View

Introduction: Diabetes and other related disorders, such as hypertension, are involved in diabetic retinopathy (DR), a chronic, progressive disease of the retinal microvasculature that threatens vision. The retinal pre-capillary arterioles, capillaries, and venules are impacted by DR. Hyperglycemia damages capillary walls, endothelial cells, retinal cells, and capillary pericytes. It also thickens the capillary basement membrane. The blood-retina barrier is broken down by microangiopathy, which can result in retinal edema, bleeding, lipid leakage (hard exudates), micro-aneurysms, hemorrhages, ischemia, and intraretinal microvascular abnormalities. Materials and Methods: Ayurveda classical texts along with the internet sources such as Google Scholar and PubMed were reviewed upon to collect the literature available as per the aims of the present article. Discussion and Conclusion: In Ayurveda, DR can be understood as Pramehajanya Timira. Due to prolonged uncontrolled hyperglycemia, two types of pathology in Madhumeha: Dhatukshayajanya and Avaranajanya play a crucial role in the development of DR. Dhatus are expelled from the body in Dhatukshaya, which leads to several pathogenic events and the development of DME. Attipravritti, Sanga, Siragranthi, and Vimarga Gamana are the four varieties of Srotodusti that are known to be important in the development of DR and macular edema.

Development of heterogenous capillary membranes with programmable properties made of PEBA copolymer for CO2 removal and testing their properties

Development of heterogenous capillary membranes with programmable properties made of PEBA copolymer for CO2 removal and testing their properties

Syndromes of gas exchange disorders in patients with pulmonary tuberculosis

Introduction. Measurement of diffusion in the lung is important in the diagnosis and management of most pulmonary diseases. The analysis of diffusion lung capac-ity (DLCO) in combination with body plethysmography is useful for the interpretation of the causes of pulmo-nary gas exchange disorders. The aim: to determine the leading syndromes of pulmonary gas exchange disorders in patients with pulmonary tuberculosis (PT). Materials and methods. 608 patients (244/364 M/W) with veri-fied PT with smoking history of less than 10 pack/years were examined. Spirometry, body plethysmography, and DLCO were performed by the single-breath breath-hold-ing method. Results. DLCO decrease was detected in the majority of patients with PT (76%): in 94% of patients with massive fibrous-cavernous PT, 79.4% with disseminated PT and more than 60% of patients with infiltrative foci, local cavities, tuberculomas. In patients without ventilation dis-orders (58.4%), DLCO decrease was caused by damage to the alveolar capillary membrane, less often by air trapping (35.1%), other cases were rare. In the obstructive variant, mixed disorders of gas exchange (38.2%) and air trapping (34.1%) were most typical. In the restrictive variant, gas exchange surface reduction (62.5%) and mixed disorders (30%) prevailed. In mixed ventilation disorders, the mixed pulmonary gas exchange disorders were most often de-tected (63.8%) and the gas exchange surface reduction was quite common (36.2%) also. Conclusion. Alveolar cap-illary membrane damage (35.1%) and air trapping (28.1%) were most common in patients with PT. The mixed variant and gas exchange surface reduction were detected less frequently (24.7 and 12.1%, respectively), but these syn-dromes led to the most significant DLCO decrease.

Standardized Oral Urea for the Treatment of Hyponatraemic Conditions: Pharmacological and Pharmacoeconomic Consideration

Standardized Oral Urea for the Treatment of Hyponatraemic Conditions: Pharmacological and Pharmacoeconomic Consideration

Membrane Distillation Crystallizer Applied for Separation of NaCl Solutions Contaminated with Oil.

In the present study, the membrane crystallizer was used to separate a saturated NaCl solution contaminated with an oil emulsion. The crystallizer was connected via a mesh separator with a feed tank in which capillary submerged modules were assembled. The effect of scaling and oil sorption on the wetting of polypropylene (PP) membranes has been investigated during the long-term studies. It has been found that cooling the solution in the crystallizer by 15 K below the feed temperature resulted in intensive NaCl crystallization in the zone below the mesh separator. A result, the salt crystallization on the membrane surface was eliminated. Contamination of saturated brines with oil in the concentration exceeding 100 mg/L caused the oil penetration into the membrane pores. The application of a PP net assembled on the capillary membranes surface reduced the intensity of wetting phenomenon caused by scaling and the oil sorption, which provides a stable membrane module performance during 1300 h test.

Autopsy Pathology of Diabetic Nephropathy with Hypertensive Cardiovascular Disease and Anemic Heart Failure

An autopsy was performed at Abia State University Teaching Hospital, Aba, Nigeria on a 58 year old woman who was known to be diabetic and hypertensive. Results of autopsy findings showed that the external description was cachectic, severely pale, cyanosed and jaundiced. The thorax, abdominal and pelvic organs were in their normal anatomic position. The trachea mucosa was hyperemic. The bronchi contained frothy fluid. The parietal pleural was shiny and smooth. The heart was enlarged and flabby. The parietal pericardium was smooth and shiny and not attached to the visceral pericardium. The tongue was pale, furred and have prominent papillae. The esophageal mucosa was hyperaemic. The cut sections of the liver showed a nutmeg appearance. The thymus was vestigial. The cut surfaces were cream colored and solid. The thyroid was grossly normal in size. The cut surfaces were brownish and showed colloid in areas. Both kidneys were grossly normal. The cut sections showed loss of corticomedullary differentiation. There were bilateral multicystic swellings on both ovaries. The cranium was intact with no fracture in the skull. The cerebral vessels showed few fatty streaks but no aneurysmal dilatation. Histologic section of the kidney showed numerous glomeruli with varying degree of sclerosis, and capillary basement membrane thickening. The cause of death was anemic heart failure, metastatic serous cystadenocarcinoma, and diabetic nephropathy with hypertensive cardiovascular disease. Thorough autopsies on all deaths of heart failure to study other associated pathologies was recommended. Keywords: Autopsy, Anemic Heart Failure, Hypertensive Cardiovascular Disease, Diabetic Nephropathy, Histology

Store-operated Ca2+ channel signaling: Novel mechanism for podocyte injury in kidney disease.

Studies over the last decade have markedly broadened our understanding of store-operated Ca2+ channels (SOCs) and their roles in kidney diseases and podocyte dysfunction. Podocytes are terminally differentiated glomerular visceral epithelial cells which are tightly attached to the glomerular capillary basement membrane. Podocytes and their unique foot processes (pedicels) constitute the outer layer of the glomerular filtration membrane and the final barrier preventing filtration of albumin and other plasma proteins. Diabetic nephropathy and other renal diseases are associated with podocyte injury and proteinuria. Recent evidence demonstrates a pivotal role of store-operated Ca2+ entry (SOCE) in maintaining structural and functional integrity of podocytes. This article reviews the current knowledge of SOCE and its contributions to podocyte physiology. Recent studies of the contributions of SOC dysfunction to podocyte injury in both cell culture and animal models are discussed, including work in our laboratory. Several downstream signaling pathways mediating SOC function in podocytes also are examined. Understanding the pivotal roles of SOC in podocyte health and disease is essential, as SOCE-activated signaling pathways are potential treatment targets for podocyte injury-related kidney diseases.

The impairment of intramural periarterial drainage in brain after subarachnoid hemorrhage

Interstitial fluid (ISF) from brain drains along the basement membranes of capillaries and arteries as Intramural Periarterial Drainage (IPAD); failure of IPAD results in cerebral amyloid angiopathy (CAA). In this study, we test the hypothesis that IPAD fails after subarachnoid haemorrhage (SAH). The rat SAH model was established using endovascular perforation method. Fluorescence dyes with various molecular weights were injected into cisterna magna of rats, and the pattern of IPAD after SAH was detected using immunofluorescence staining, two-photon fluorescent microscope, transmission electron microscope and magnetic resonance imaging tracking techniques. Our results showed that fluorescence dyes entered the brain along a periarterial compartment and were cleared from brain along the basement membranes of the capillaries, with different patterns based on individual molecular weights. After SAH, there was significant impairment in the IPAD system: marked expansion of perivascular spaces, and ISF clearance rate was significantly decreased, associated with the apoptosis of endothelial cells, activation of astrocytes, over-expression of matrix metalloproteinase 9 and loss of collagen type IV. In conclusion, experimental SAH leads to a failure of IPAD, clinically significant for long term complications such as CAA, following SAH.

The effects of fibers layer assembled on the capillary membranes applied for separation of brines by membrane distillation

The wetting of hydrophobic membranes caused by scaling phenomenon is the main issue that may constraint the successful applications of membrane distillation (MD) and membrane crystallization, especially during implementation of the Zero Liquid Discharge technologies. In this work, the submerged polypropylene modules were applied for separation of saturated NaCl solutions. The idea that membranes wetting can be reduced when the salts crystallize on the macrostructures covering the membrane surface is presented. To verify this idea, the effect of utilization of protective fibers layer assembled on the capillary membranes on the process performance was investigated. The permeate flux decreased 90% when the salt crystals covered membranes, thus the deposit was periodically dissolved. This operation accelerated the pore wetting and as a result the distillate conductivity increased from 5 to 200 μS/cm. On the contrary, the conductivity increased only to 20 μS/cm for membrane covered by fibers layer. In this case the salt crystalized mainly on the fibers surface, thus the salt dissolution did not wet the pores. The SEM studies confirmed that the fibers layer reduced the formation of salt deposits directly on the membrane surface. In the case of nonprotected membrane, a large amount of NaCl crystals were formed inside the membrane pores, which caused a mechanical damage of the membrane matrix. The scaling intensity and membrane wettability were studied during long-term tests, carried out over 2000 h. It has been found that the application of fibers layer allows to maintain the membranes durability despite intensive scaling phenomenon. In this case, it is essential to obtain mixing conditions in the boundary layer that ensure the feed flow inside the fibers layer.

841 ASSOCIATION BETWEEN CARDIORESPIRATORY SYMPTOMS AND LUNG FUNCTION IN PATIENTS WITH LONG-COVID SIGNS

Abstract Background Many patients recovered from COVID-19 infection present a variety of symptoms which limits overall quality of life, as reduced exercise performance, dysfunctional breathing, cough, dyspnea, weakness and anxiety. This condition has been named long COVID. The origin of this symptomatology is still unclear. This study has the aim to analyse the relation between symptoms and respiratory function, focusing on the alveolar capillary membrane. Methods Consecutive patients with long COVID 19 symptoms after 6 months were included. Patients underwent full clinical evaluation, laboratory tests, echocardiography, thoracic CT scan, spirometry including alveolar capillary membrane diffusion by means of combined carbon dioxide and nitric oxide lung diffusion (DLCO/DLNO) and cardiopulmonary exercise test. We measured surfactant derive protein B (immature form) as blood marker of alveolar capillary function. A questionnaire allowed to evaluate symptoms. Results We evaluated 204 post COVID-19 patients (age 56.5±14.5 y, 89 females (44%), BMI 25.7±4.0, 6% active smokers) referring to our hospital 171±85 days after the end of acute COVID-19 infection (Fig. 1). None of spirometry data was associated with long COVID 19 referred symptoms. SPB was not associated to differences in any of the referred symptoms. Subjects with lower capillary volume (VCap) have more frequently dyspnea, tiredness, fatigability and hair loss (Fig.2). CT scan lung damage correlated with SPB and membrane diffusion but not with VCap, exercise performance or VE/VCO2 slope. The strongest correlation of SPB were with lung parenchyma damage and Vcap. Conclusions Our data suggest that a relevant reduction of alveolar capillary membrane function plays a central role in the long COVID cardiorespiratory symptoms.

Torularhodin bilosomes attenuate high-fat diet-induced chronic kidney disease in mice by regulating the TLR4/NF-κB pathway

Torularhodin is a carotenoid that exerts beneficial effects on chronic kidney disease (CKD), which is strongly linked to a high-fat diet (HFD), however, its functional properties have not yet been fully determined. In this study, torularhodin bilosomes, which feature good processing properties and physical stability, were chosen for delivery. We evaluated their effect on mice with CKD induced by HFD and determined the relevant mechanisms. In HFD-fed mice, both structural and functional renal injury was observed, including significant increases in BUN, SCr, urinary protein levels, capillary basement membrane thickening, and inflammatory cell infiltration. The results showed that SOD content, GSH-px content, and CAT activity were all significantly higher, while the MDA level was significantly lower in the tor-emu and tor-bilo groups, indicating that torularhodin effectively alleviated oxidative stress. In addition, the expression of the inflammatory factors TNF-a, IL-6, and IL-1β was reduced in the torularhodin group compared with the model group, and both the transcription and expression of the TLR4, MyD88, TIRAP, TRIF, and NF-κB proteins related to the TLR4/NF-κB pathway were reduced. Mechanistically, torularhodin reduced the renal inflammatory response by decreasing TLR4 protein expression and the signaling of proteins such as MyD88, as well as preventing NF-κB from undergoing dissociation, reducing its transcriptional activity, and decreasing the release of downstream pro-inflammatory mediators. In conclusion, torularhodin bilosomes can alleviate high-fat diet-induced CKD in mice by modulating the TLR4/NF-κB pathway. This result further deepens the understanding of torularhodin activity and confirms the role of torularhodin as an effective health supplement.

Evaluation of an ultrafiltration membrane for the removal of fish viruses and bacteria in aquaculture water

Ultrafiltration (UF) membranes are used to successfully remove waterborne virus and bacteria from wastewater and drinking water. However, UF membrane application in aquaculture water treatment is limited. In this study we evaluate the performance of a capillary polyethersulfone UF membrane to remove two benchmark waterborne fish pathogens: i) the infectious pancreatic necrosis virus - IPNV, which is an unenveloped icosahedral virus, and ii) the bacterium Aeromonas salmonicida, which is a Gram-negative, facultative anaerobic bacilli. Moreover, the UF membrane bench-scale unit was tested at two temperatures according to salmonid aquaculture: low (4 - 7°C) and high (16 - 19°C). Sterilised natural seawater was spiked with laboratory cultured pathogens, the water was filtrated, and the membrane permeate collected. Both pathogen solution and permeate were evaluated using a cell culture method to estimate the colony-forming units (CFU/ml) for bacteria presence, a median tissue culture infectious dose (TCID50/ml) assay for virus presence, and real-time quantitative polymerase chain reaction (RT-qPCR) for both bacteria and virus presence. The membrane permeate was negative for both virus and bacteria for all analysis and for both low and high temperatures. The results from this bench-scale study are encouraging for the application of UF membrane technology in aquaculture water treatment to prevent virus and bacteria outbreaks. Further studies should validate this UF membrane technology results in commercial aquaculture conditions.

Preparation of Polysulfone Capillary Ultrafiltration Membranes for Pre-treatment of Sea Water Reverse Osmosis and Studies on its Fouling behavior after Turbidity Removal from Sea Water

Preparation of Polysulfone Capillary Ultrafiltration Membranes for Pre-treatment of Sea Water Reverse Osmosis and Studies on its Fouling behavior after Turbidity Removal from Sea Water

Computational pulmonary edema: A microvascular model of alveolar capillary and interstitial flow.

We present a microvascular model of fluid transport in the alveolar septa related to pulmonary edema. It consists of a two-dimensional capillary sheet coursing by several alveoli. The alveolar epithelial membrane runs parallel to the capillary endothelial membrane with an interstitial layer in between, making one long septal tract. A coupled system of equations is derived using lubrication theory for the capillary blood, Darcy flow for the porous media of the interstitium, a passive alveolus, and the Starling equation at both membranes. Case examples include normal physiology, cardiogenic pulmonary edema, noncardiogenic edema Acute Respiratory Distress Syndrome (ARDS) and hypoalbuminemia, and the effects of positive end expiratory pressure. COVID-19 has dramatically increased ARDS in the world population, raising the urgency for such a model to create an analytical framework. Under normal conditions, the fluid exits the alveolus, crosses the interstitium, and enters the capillary. For edema, this crossflow is reversed with the fluid leaving the capillary and entering the alveolus. Because both the interstitial and capillary pressures decrease downstream, the reversal can occur within a single septal tract, with edema upstream and clearance downstream. Overall, the interstitial pressures are found to be significantly more positive than values used in the traditional physiological literature that creates steep gradients near the upstream and downstream end outlets, driving significant flows toward the distant lymphatics. This new physiological flow may provide a possible explanation to the puzzle, noted since 1896, of how pulmonary lymphatics can function so far from the alveoli: the interstitium can be self-clearing.

Diffuse alveolar hemorrhage: a narrative review

This review discusses clinical presentation of DAH, diagnosis of the underlying histology’s, treatment options, as well as morbidity and mortality rates. Diffuse alveolar hemorrhage (DAH) is considered a life-threatening pulmonary complication in patients with systemic autoimmune disorders, hematologic malignancies, and coagulation disorders. DAH is distinguished by acute onset of hypoxia and alveolar infiltrates that may lead to progressive alveolar bleeding. Early diagnosis and recognition are crucial for survival. Treatment for DAH involves treating both the underlying condition and the autoimmune damage of the alveolar capillary membrane. The gold standard is immunosuppressive agents and corticosteroids. Despite early recognition and proper treatment DAH mortality rates remain high.

The effect of gestataional hypertension on the ultrastructural structure of the placenta

The objective: to study pathological changes and compensatory-adaptive reactions in the structural and ultrastructural components of the placental barrier in pregnant women with gestational arterial hypertension, who received magnesium preparations. Materials and methods. 100 patients with gestational hypertension were examined. The presence of magnesium deficiency in these women was determined by the results of our questionnaires.Pathomorphological and electronic microscopic examination of 32 placentas of patients with gestational hypertension was carried out. 12 placentas of them were from pregnant women who received the proposed management of pregnancy, which included magnesium drugs (I group), and 11 placentas – from patients with risk of preeclampsia, who were observed with the use of standard approaches of pregnancy for women with the risk of preeclampsia (II group). Control group included the results of pathomorphological and electronic microscopic study of 9 placentas from healthy women.Results. Placental of women with gestational hypertension have structural features, which is manifested by the mosaic change of placental barrier in the form of uneven circulatory disorders with hemorrhages and stasis (at the ultrastructural level) in the fetal microvessels of the villi, reducing the placental functional area (rapprochement of the villi), presence of stromal sclerosis villi, foci of pathological immaturity, increase in calcium salts (mineral dystrophy) on the background of compensatory reactions. Electronic microscopic study of the placentas in the I group revealed an increase in the compensatory-adaptive reactions of the placenta – thinning of the placental barrier, activation of cytotrophoblast cells in the placental barrier, increase the number of syncytiocapillary membranes in terminal villi with syncytiotrophoblast organic activation, increase in the number of ribosomes, the appearance of orthodox configuration of mitochondria, increasing the number of capillary membranes and thinning of syncytia, reducing the number of sludge phenomena in microvessels, which leads to an increase in the possibility of nutrient transfer from mother to fetus, etc.Conclusions. The use of the proposed therapy, which involves magnesium, diosmin and others substances, leads to a significant decrease in the frequency of detection of pathological changes in structural and ultrastructural components of the placental barrier and increased compensatory-adaptive reactions which can be considered the result of the positive impact of the proposed therapy on the placental ultrastructural elements in women with risk of preeclampsia.