Role of cyclooxygenases 1 and 2 in the maintenance of colonic mucosal integrity in an experimental colitis model.

The role of cyclooxygenase (COXs) isoforms in maintaining colonic mucosal integrity is not fully understood. This study aimed to evaluate the role of COX-1 and -2 on colonic mucosal integrity in an experimental colitis model. Colitis was induced in Wistar rats by intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid (20 mg + 50% ethanol). The control group (sham group) received saline only. After 7, 14, or 28 days, colonic samples were removed, and macroscopic lesion scores, wet weight, myeloperoxidase activity, and transepithelial electrical resistance (TER) were determined. In other rat groups, colonic samples from the sham group and a 7th day post-colitis group were mounted in Üssing chambers with the luminal side exposed to a buffer solution (control), acetylsalicylic acid (ASA), SC-560 (COX-1 inhibitor), or celecoxib (COX-2 inhibitor). TER and epithelial permeability to fluorescein were measured. The 7th day colitis group had higher macroscopic damage scores, wet weight, and myeloperoxidase activity and lower basal TER than the sham, 14th day colitis, and 28th day colitis groups. Inhibition of COX-1 but not COX-2 significantly decreased TER and increased permeability to fluorescein in the 7th day post-colitis group compared to the sham group. Additionally, ASA decreased the colonic mucosal integrity on day seven post-colitis compared to the sham group. A decrease in the colonic mucosa integrity in the experimental colitis model can be aggravated only by the inhibition of COX-1, which demonstrated the importance of this enzyme in the maintenance of colonic mucosal integrity.

Role of cyclooxygenases 1 and 2 in the maintenance of colonic mucosal integrity in an experimental colitis model

The role of cyclooxygenase (COXs) isoforms in maintaining colonic mucosal integrity is not fully understood. This study aimed to evaluate the role of COX-1 and -2 on colonic mucosal integrity in an experimental colitis model. Colitis was induced in Wistar rats by intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid (20 mg + 50% ethanol). The control group (sham group) received saline only. After 7, 14, or 28 days, colonic samples were removed, and macroscopic lesion scores, wet weight, myeloperoxidase activity, and transepithelial electrical resistance (TER) were determined. In other rat groups, colonic samples from the sham group and a 7th day post-colitis group were mounted in Üssing chambers with the luminal side exposed to a buffer solution (control), acetylsalicylic acid (ASA), SC-560 (COX-1 inhibitor), or celecoxib (COX-2 inhibitor). TER and epithelial permeability to fluorescein were measured. The 7th day colitis group had higher macroscopic damage scores, wet weight, and myeloperoxidase activity and lower basal TER than the sham, 14th day colitis, and 28th day colitis groups. Inhibition of COX-1 but not COX-2 significantly decreased TER and increased permeability to fluorescein in the 7th day post-colitis group compared to the sham group. Additionally, ASA decreased the colonic mucosal integrity on day seven post-colitis compared to the sham group. A decrease in the colonic mucosa integrity in the experimental colitis model can be aggravated only by the inhibition of COX-1, which demonstrated the importance of this enzyme in the maintenance of colonic mucosal integrity.

Role of TRPV1 receptor in inflammation and impairment of esophageal mucosal integrity in a murine model of nonerosive reflux disease.

BACKGROUND: Microscopic inflammation and impairment of the esophageal epithelial barrier are considered relevant for perception of symptoms in patients with nonerosive reflux disease (NERD). In these patients, the receptor transient receptor potential vanilloid 1 (TRPV1) is overexpressed in the esophageal mucosa, but its role is not yet fully understood. We evaluated the role of TRPV1 in esophageal inflammation and mucosal barrier impairment in a murine model of NERD. METHODS: Nonerosive reflux disease was surgically induced in Swiss mice by pyloric substenosis and ligature of the gastric fundus, and the mice were killed 7 days post surgery. The experimental groups were: I, sham surgery (negative control); II, NERD untreated; III and IV, NERD + SB366791 or capsazepine (TRPV1 antagonists); and V, NERD + resiniferatoxin (for long-term desensitization of TRPV1). The esophagus was collected for western blotting and histopathology and for evaluation of wet weight, myeloperoxidase (MPO), keratinocyte-derived chemokine (KC), transepithelial electrical resistance (TEER), and basal permeability to fluorescein. KEY RESULTS: Compared to sham, NERD mice had increased esophageal wet weight and MPO and KC levels. The mucosa had no ulcers but exhibited inflammation. NERD mice showed mucosal TRPV1 overexpression, a more pronounced decrease in TEER at pH 0.5 (containing pepsin and taurodeoxycholic acid), and increased basal permeability. Pharmacological modulation of TRPV1 prevented esophageal inflammation development, TEER changes by acidic exposure, and increase in esophageal permeability. CONCLUSIONS & INFERENCES: The TRPV1 receptor has a critical role in esophageal inflammation and mucosal barrier impairment in NERD mice, suggesting that TRPV1 might be a pharmacological target in patients with NERD.

Histological evaluation and E-cadherin and ß-catenin expression in kidney of dogs submitted to renal ischemia and reperfusion after chlorpromazine administration / Avaliação histológica e imunomarcação de E-caderina e ß-catenina em rins de cães submetidos a isquemia e referfusão renal após administração de clorpromazina

Renal ischemia can be associated with some urological procedures, such as renovascular surgery or kidney transplantation, that are often followed by acute renal failure. The aim of this study was to verify the E-cadherin and ß-catenin localization in canine kidney in different times of renal ischemia and reperfusion after chlorpromazine application. Twelve dogs were randomly distributed equally into two groups. GroupA with ischemia and reperfusion without chlorpromazine and groupB with ischemia and reperfusion treated by chlorpromazine. GroupB received intravenous chlorpromazine, 15 min before the artery obstruction, which lasted 1 hour. After this period, the clamps in the renal arteries were released and the organ remained in reperfusion for 2 hours. In each group, anti-E-cadherin and anti-ß-catenin antibodies were made in six tissue samples from renal parenchyma. E-cadherin and ß-catenin are differentially expressed in segments from cortex and medulla in dog's kidneys and the use of chlorpromazine did not alter the expression of both proteins. Occlusion of the left renal artery in dogs causes morphological alterations mainly in proximal convoluted tubules, beginning 30min after the start of ischemia and being aggravated after two hours of reperfusion. These results reveal that chlorpromazine did not change kidneys' histological aspect nor E-cadherin and ß-catenin expression.(AU)

A lesão renal isquêmica pode estar associada a procedimentos urológicos, tais como cirurgia renovascular, cirurgia renal extracorpórea ou transplante renal. Essa injúria, muitas vezes, é seguida de insuficiência renal aguda. O objetivo deste trabalho foi observar a localização da E-caderina e da ß-catenina em rim de cães, além de relacionar a expressão dessas proteínas das junções de aderência em diferentes tempos de isquemia e reperfusão com ou sem a aplicação de clorpromazina. Para tanto, foram utilizados 12 cães, distribuídos aleatoriamente em dois grupos de seis indivíduos: grupo A, com isquemia e reperfusão sem tratamento por clorpromazina, e o grupo B, com isquemia e reperfusão tratado por clorpromazina. No procedimento cirúrgico, foi realizada uma incisão paracostal esquerda para identificação e isolamento do rim esquerdo e da artéria renal esquerda. Após o isolamento da artéria, os animais de todos os grupos tiveram o vaso ocluído. Os animais do grupo B receberam clorpromazina via endovenosa, na dose de 5mg/kg, 15min antes da clampagem do vaso, que durou uma hora. Após este período, as artérias renais foram desobstruídas e os órgãos permaneceram em reperfusão por duas horas. Em cada grupo, foram extraídas seis amostras de parênquima renal, com utilização de agulha tru-cut, para marcação com anticorpos anti-E-caderina e anti-ß-catenina por meio de imunoistoquímica. E-caderina e ß-catenina são diferencialmente expressas em segmentos do córtex e da medula em rim de cães e o uso da clorpromazina não alterou a expressão das duas proteínas.(AU)

Use of Seeds as Fungus Garden Substrate Changes the Organization of Labor Among Leaf-Cutting Ant Workers.

Seeds of different plant species constitute an alternative but also significant substrate that leaf-cutting ants use to cultivate their fungus garden. However, how they are processed inside the nest and if their use implies differential allocation of worker size classes are still poorly known. Using laboratory colonies of Acromyrmex subterraneus (Forel) as a model, the behaviors related to the processing of three different seeds (sesame, guava, and grape) as fungus substrate were listed. At the same time, we measured how each worker size class contributed to the execution of these behaviors by registering their respective frequency. It was found that medium-sized (1.2 > head width < 1.6 mm) and minimum-sized (head width <1.1 mm) workers assumed the role of incorporation for sesame and grape seeds, respectively. Major-sized workers (head width >1.7 mm) were concentrated on licking and holding guava seeds. Tegument removal was the only task observed that differs between treatment of seeds and treatment of leaves before their incorporation, as described in the literature. It was verified that different species of seeds imply a differential allocation of worker size classes and the inclusion or exclusion of some tasks from the behavioral repertoire. Regardless of the substrate type, leaf-cutting ant workers follow a coordinated and specialized procedure to cultivate the fungus garden but always maintain a high degree of cooperation.

Description of immature stages and development time of Paralucilia paraensis (Mello) (Diptera: Calliphoridae) associated with the decomposition of a partially submerged swine carcass.

We report on the bionomics and morphology of the immature stages of Paralucilia paraensis (Mello) (Diptera: Calliphoridae). Observations were made on a daily basis for 10 h (from 8 a.m. to 6 p.m.) on a 45-kg pig (Sus scrofa) whose carcass had been partially submerged in a stream of water on the 21st of November 2009, in a forested area of Manaus, Amazonas, Brazil. The collected specimens were placed in plastic vials and transferred to a growth chamber maintained at room temperature. Adults of P. paraensis were collected on the carcass between the 3rd and the 18th days. A total of 13 gravid females were captured; from these, 1,240 eggs were obtained and yielded 1,030 larvae that developed into 879 adults. The average time required for hatching was 13 h. On average, the larvae reached the second instar within 13 h, third instar within 18 h, and pupae within 46 h. The pupal stage lasted 96 h. The complete development time was 216 h. This is the first report on the development time and morphology of immature stages of P. paraensis in forested areas. Therefore, these results provided information for the implementation of future forensic studies in the state of Amazonas.

Oxacilin-resistant Coagulase-negative staphylococci (CoNS) bacteremia in a general hospital at São Paulo city, Brasil / Bacteremias por Staphylococcus coagulase negativos oxacilina resistentes em um hospital na cidade de São Paulo, Brasil

In the last decades, coagulase-negative staphylococci (CoNS), especially Staphylococcus epidermidis have become an important cause of bloodstream infections. In addition, rates of methicillin-resistance among CoNS have increased substantially, leading to the use of glicopeptides for therapy. The objective of this study was to evaluate eleven consecutives clinically relevant cases of oxacillin-resistant CoNS bacteremia in a general hospital localized in São Paulo city, Brazil. Five different species were identified by different phenotypic methods, including S. epidermidis (5), S. haemolyticus (3), S. hominis (1), S. warneri (1) and S. cohnii subsp urealyticus (1). A variety of Pulsed Field Gel Electrophoresis profiles was observed by macrorestriction DNA analysis in S. epidermidis isolates, but two of three S. haemolyticus isolates presented the same profile. These data indicated the heterogeneity of the CoNS isolates, suggesting that horizontal dissemination of these microorganisms in the investigated hospital was not frequent. One S. epidermidis and one S. haemolyticus isolates were resistant to teicoplanin and susceptible to vancomycin. The selective pressure due to the use of teicoplanin in this hospital is relevant.

Staphylococcus coagulase negativos (SCoN), especialmente Staphylococcus epidermidis tem se tornado causa importante de infecções da corrente circulatória nas últimas décadas. Além disso, percentuais de resistência a meticilina entre os SCoN têm aumentado significativamente, levando ao uso de glicopeptídeos nestes pacientes. O objetivo deste estudo foi avaliar onze casos consecutivos de bacteremia clinicamente relevantes por SCoN oxacilina resistentes em um hospital localizado na cidade de São Paulo, Brasil. Cinco diferentes espécies foram identificadas por diferentes métodos fenotípicos, incluindo S. epidermidis (5), S. haemolyticus (3), S. hominis (1), S. warneri (1) e S. cohnii subsp urealyticus (1). Diferentes perfis eletroforéticos obtidos pela técnica de "Pulsed Field Gel Electrophoresis" foram observados na análise da macrorestrição do DNA nos isolados de S. epidermidis, mas dois dos três isolados de S. haemolyticus apresentaram o mesmo perfil. Esses dados indicam uma heterogeneidade nos isolados SCoN, sugerindo que a disseminação horizontal no hospital investigado não é freqüente. Um isolado de S. epidermidis e um de S. haemolyticus foram resistentes à teicoplanina e sensíveis à vancomicina. Observa-se a relevância da pressão seletiva pelo uso de teicoplanina nos pacientes deste hospital.

Oxacilin-resistant Coagulase-negative staphylococci (CoNS) bacteremia in a general hospital at São Paulo city, Brasil.

In the last decades, coagulase-negative staphylococci (CoNS), especially Staphylococcus epidermidis have become an important cause of bloodstream infections. In addition, rates of methicillin-resistance among CoNS have increased substantially, leading to the use of glicopeptides for therapy. The objective of this study was to evaluate eleven consecutives clinically relevant cases of oxacillin-resistant CoNS bacteremia in a general hospital localized in São Paulo city, Brazil. Five different species were identified by different phenotypic methods, including S. epidermidis (5), S. haemolyticus (3), S. hominis (1), S. warneri (1) and S. cohnii subsp urealyticus (1). A variety of Pulsed Field Gel Electrophoresis profiles was observed by macrorestriction DNA analysis in S. epidermidis isolates, but two of three S. haemolyticus isolates presented the same profile. These data indicated the heterogeneity of the CoNS isolates, suggesting that horizontal dissemination of these microorganisms in the investigated hospital was not frequent. One S. epidermidis and one S. haemolyticus isolates were resistant to teicoplanin and susceptible to vancomycin. The selective pressure due to the use of teicoplanin in this hospital is relevant.

The loss of ions from Venus through the plasma wake.

Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. Present-day thermal escape is low for all atmospheric species. However, hydrogen can escape by means of collisions with hot atoms from ionospheric photochemistry, and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed to escape through interaction with the solar wind. Nevertheless, their relative rates of escape, spatial distribution, and composition could not be determined from these previous measurements. Here we report Venus Express measurements showing that the dominant escaping ions are O+, He+ and H+. The escaping ions leave Venus through the plasma sheet (a central portion of the plasma wake) and in a boundary layer of the induced magnetosphere. The escape rate ratios are Q(H+)/Q(O+) = 1.9; Q(He+)/Q(O+) = 0.07. The first of these implies that the escape of H+ and O+, together with the estimated escape of neutral hydrogen and oxygen, currently takes place near the stoichometric ratio corresponding to water.

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express.

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.

Teste de esforço: alteraçöes do segmento ST retritas à fase de recuperaçäo / Exercise testing: abnormal ST segments restrict to recovery phase

Objetivo. Determinar a incidência de doença coronária aterosclerótica (DCA) e/ou isquemia miocárdica em pacientes (pt) com alteraçoes do segmento ST restrita à fase de recuperaçao (ASTRR) do teste ergométrico. Casuística e Método. Estudo retrospectivo em 19 pacientes nao consecutivos com ASTRR, através da cinecoronariografia e/ou cintigrafia de esforço planar. Amostra de 18 homens, uma mulher, com idade de 58 + 9 anos, 18 sintomáticos. Resultados. ASTRR corresponderam a segmentos ST infra-desnivelados de 1 a 4 mm da linha de base, com inversao da onda T durante a recuperaçao precoce (2pt), tardia (14 pt). Foi documentada DCA em 14 pt (nove submetidos à cirurgia de revascularizaçao); miocardiopatia hipertensiva com coronárias normais em 3 pt e prolapso de válvula mitral em 1 pt. Em 13 casos a cinecoronariografia eóu cintilografia de esforço foram realizados dentro de seis meses do Teste Ergométrico, sendo a presença de DCA e ou isquemia miocárdica detectada em 8 pt. Em 3 pt, testes ergométricos sucessivos mostraram ASTRR reprodutíveis em dois casos. Conlusao. Os autores relatam a elevada prevalência de DCA e ou hipoperfusao transitória na cintigrafia de esforço em homens sintomáticos de meia idade com ASTRR no teste de esforço.

Multiwavelength operation with thin diffractive elements.

It is generally accepted that diffractive elements designed for multiwavelength operation require deep surface-relief profiles. We show, however, that thin diffractive elements can be designed to operate with more than one wavelength. A novel, to our knowledge, optimization technique is introduced for this purpose. The maximum phase delay is limited to only a few multiples of 2pi, and the element can implement different functions for different wavelengths. Examples with fan-out gratings are discussed.

Characterization of attenuated proestrous luteinizing hormone surges in middle-aged rats by deconvolution analysis.

Reproductive aging in female rats is associated with attenuated preovulatory LH surges. In this study, detailed analyses of the episodic characteristics of the proestrous LH surge were conducted in young and middle-aged regularly cyclic rats. On proestrus, blood samples were withdrawn at 3-min intervals for 6 h and analyzed for LH concentrations by RIA in triplicate. Deconvolution analysis of immunoreactive LH concentrations revealed that there was no difference in the detectable LH secretory burst frequency between young and middle-aged rats. However, in middle-aged rats with an attenuated LH surge on proestrus, the mass of LH secreted per burst and the maximal rate of LH secretion per burst were only one fourth (p < 0.01) of those in young and middle-aged rats with normal LH surges. Furthermore, middle-aged rats with attenuated LH surges had a 4-fold decrease (p < 0.01) in the maximal rate of LH secretion per burst compared to young and middle-aged females with normal LH surges. The apparent half-life of endogenous LH was similar among the 3 groups. The attenuated LH surges of middle-aged rats were related specifically to a decrease in LH burst amplitude with no change in pulse frequency. The orderliness of moment-to-moment LH release as quantified by the regularity statistic, approximate entropy, was comparable in the 3 groups. Our findings of a markedly decreased amount of LH released per burst and preserved orderliness of the LH release process strongly suggest that a deficient GnRH drive and/or reduced responsivity to the GnRH signal, rather than altered timing of the signal, accounts for the age-related decline in reproductive function in female rats as presaged by an attenuated proestrous LH surge in middle age.

Intestinal adaptation in short bowel syndrome without tube feeding or home parenteral nutrition: report of four consecutive cases.

Because home total parenteral nutrition (TPN) is not available to most of the Brazilian population, an alternative treatment for short bowel syndrome was evaluated. Four patients ages 40-65 y (mean: 53.75 +/- 10.59), three with mesenteric thrombosis, and one with Crohn's disease were studied. The average length of the remaining small bowel in these patients was 54.5 +/- 6.4 cm; the ileocecal valve was preserved in 3 cases. A progressive step diet was used for intestinal adaptation. Administration of pectin was started at the beginning of the special oral diet (step 1), followed by medium-chain triacylglycerols (MCTs) and complex, nonfermentable sugars (step 2); coconut oil (47% MCTs) and simple sugars (step 3); and long-chain triacylglycerols and lactose (step 4). TPN was interrupted at step 3 or 4 when the energy content of the diet reached 150% of the patient's resting energy expenditure, if serum albumin and weight were stable or increasing, and if the frequency, amount, and consistency of stools remained unchanged. Nutritional follow-up showed that patients responded well to this approach; also, patients returned to their previous professional activities. Thus, enteral formulas were not essential for gastrointestinal adaptation. Home TPN should not be indicated on the basis of strict criteria, but rather when a patient fails to adapt to a progressive, special oral diet.

Beta-spectrin Campinas: a novel shortened beta-chain variant associated with skipping of exon 30 and hereditary elliptocytosis.

Beta-Spectrin Campinas is a novel spectrin variant associated with a shortened beta-chain in a kindred with hereditary elliptocytosis (HE). The propositus and her mother exhibited increased amounts of spectrin dimers and an increase in the alphaI 74 kD fragment from the alpha-chain after partial tryptic digestion of spectrin. The shortened beta-chain appeared as an additional band of approximately 200 kD on SDS-PAGE. In order to delineate the molecular defect of this abnormality at the gene level, reticulocyte mRNA was transcribed into cDNA and the last four exons of the beta-spectrin gene were amplified. Agarose gel of the amplification product of the propositus revealed the expected band of 487 bp as well as a shortened band of approximately 300 bp (size determined on gel). This shortened cDNA amplification product was cloned and nucleotide sequencing revealed the absence of the entire exon 30. In order to determine the underlying mutation responsible for this abnormal splicing, a genomic DNA fragment containing exons 30 and 31 was amplified and nucleotide sequencing revealed a G-->A substitution at the 5' donor splice site consensus sequence of intron 30 (nt + 1 IVS30). The skip splicing observed in this study results in a frameshift, creating a new stop codon and causing a deletion of 129 amino acids at the very COOH-terminus of the protein, thus impairing spectrin dimers self-association. We classified this HE as spherocytic HE because the propositus presented a few spherocytes in addition to many elliptocytes in the blood smear, whereas her mother, who was splenectomized, showed many schizocytes, poikilocytes and spherocytes.

Fundamental limits of optical superresolution.

Increasing the resolving power of optical systems beyond the limits imposed by diffraction, or superresolution, has considerable theoretical as well as practical interest. Several schemes have been proposed to achieve superresolution with reasonable success, but there are no criteria that enable one to determine what improvement can ultimately be attained for a certain level of resolution. We have determined fundamental limits imposed on the performance of any superresolution strategy. A brief analysis indicates that current optical-superresolution techniques can still have their performance considerably augmented.

Determination of neutral polymorphisms (frameworks) of the human beta globin gene in beta thalassaemias by PCR/DGGE.

PURPOSE: Considering the importance of type beta thalassaemias as hereditary syndromes of high significance in different populations of Mediterranean origin and, by extension, in the Brazilian population, the objective of the present study was to determine by PCR/DGGE the gene structures responsible for neutral polymorphisms (frameworks) observed in the human beta globin gene associated with the mutations responsible for type beta thalassaemias in a sample of the Brazilian population and, more specifically, of the population of the State of São Paulo. PATIENTS AND METHODS: Thirty individuals with beta thalassaemic mutations were analyzed: 22 mutations were in codon 39 (C-->T), 5 in IVS1-110 (G-->A), 2 in IVS1-6 (T-->C) and 1 in IVS1-1 (G-->A). DNA was extracted and selective amplification was performed by PCR extending from position IVS1 nt 46 to IVS2 nt 126 (474 pb). The product was then analyzed by polyacrylamide gel electrophoresis on a denaturing 10-60% urea/formamide gradient. RESULTS: The results demonstrated that, as expected, the mutations responsible for type beta thalassaemia observed in this population are of Mediterranean origin, with 73% distribution represented by codon 39, 17% by IVS1-110, 7% by IVS1-6 and 3% by IVS1-1. In turn, framework distribution seems to indicate a higher frequency of Fr 1-1 in codon 39 and IVS1-110, of Fr 1-3 in IVS1-6 and of Fr 1-2 in IVS1-1. CONCLUSIONS: These results permit us to conclude that gene amplification by PCR followed by DGGE is an appropriate method for the separation of DNA molecules that differ even by a single base change and therefore can be utilized to detect the alterations observed in the human beta globin gene. This methodology shows that, using only a pair of primers, it is possible to define the frameworks that are observed in the beta globin gene.

Diffractive-refractive behavior of kinoform lenses.

The connection between the diffractive behavior and the refractive behavior of kinoform lenses is investigated. The image-forming capabilities of the diffractive element are found to be expressed as an interference pattern that is due to a set of associated refractive lenses corresponding to each zone of the kinoform. The coefficient modulating the contribution of each refracting zone is determined. The term linking the point-spread function of a refractive lens and a diffractive lens is also obtained. Spectral and spatial aspects are compared as the diffractive element approaches the refractive limit.