Relación entre los niveles séricos de proteína C reactiva y α1-antitripsina y la resistencia a la insulina en mujeres con obesidad / Relationship between serum levels of C-reactive protein and α1-antitrypsin and insulin resistance in obese women

El tejido adiposo produce citocinas implicadas en la resistencia a la insulina (RI) tales como IL-6, IL-8, TNF-α y moléculas proinflamatorias como la proteína C reactiva (PCR). La α1-antitripsina es una proteína plasmática sensible a la inflamación. El objetivo de este estudio fue determinar la correlación existente entre los niveles séricos de PCR ultrasensible (PCRus) y de α1-antitripsina con los índices de RI en mujeres venezolanas obesas. La población del estudio estuvo conformada por 15 mujeres normopeso (IMC 21,8 ± 1,9 kg/m²) y 15 mujeres con obesidad (IMC 35,3 ± 5,3 kg/m²). Se realizó a los grupos la prueba de tolerancia oral a la glucosa (carga de 75g, 2h) y se calcularon los siguientes índices: Modelo de Determinación de la Homeostasis de la resistencia a la insulina (HOMA-IR), Modelo de Determinación de la Homeostasis de la función de la célula-β (HOMA-β), Índice Matsuda e Índice Insulinogénico. Se determinó la relación entre los niveles séricos de PCRus y α1-antitripsina y estos índices. Las mujeres con obesidad presentaron mayores niveles de PCRus (p = 0,001) en comparación con las mujeres normopeso. Los niveles séricos de PCRus se correlacionaron positivamente con HOMA-IR (r= 0,73, p=0,0021), HOMA-β (r= 0,53, p=0,031) y negativamente con el Índice Matsuda (r= -0,60, p=0,017), en las mujeres con obesidad. No se observó ninguna correlación entre los niveles séricos de α1-antitripsina y los índices de RI en el grupo obeso ni en el grupo normopeso. Se encontró una relación entre los niveles séricos de PCRus y la RI, sugiriendo un rol de la inflamación subclínica en la RI.

Adipose tissue produces cytokines involved in insulin resistance (IR) such as IL-6, IL-8, TNF-α and proinflammatory molecules such as C reactive protein (CRP). α1-antitrypsin is an inflammation-sensitive plasma protein. The objective of this study is to determine the correlation between serum CRP high-sensitivity (CRPhs) and α1-antitrypsin levels with IR indices in obese Venezuelan women. The study population consisted of 15 normal weight women (BMI 21.8 ± 1.9 kg/m²) and 15 obese women (BMI 35.3 ± 5.3 kg/m²). Obese and lean women underwent a 2 h-75g oral glucose tolerance test and the following indices were calculated: homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β cell function (HOMA-β), Matsuda Index and Insulinogenic Index. The relationship between serum CRPhs and α1-antitrypsin levels and these indices were determined. Obese women had higher CRPhs levels (p = 0.001) compared with normal weight women. In obese women, serum CRPhs levels were positively correlated with HOMA-IR (r=0.73, p=0.0021), HOMA-β (r=0.53, p=0.031) and negatively correlated with the Matsuda Index (r= -0.60, p=0.017). No correlation between serum levels of α1-antitrypsin and IR indices in the obese group and the lean group was observed. There was a relation between serum CRPhs levels and insulin resistance, suggesting a role of subclinical inflammation in IR.

Serum transferrin as a liver fibrosis biomarker in patients with chronic hepatitis B

BACKGROUND/AIMS: Transferrin and alpha-1 antitrypsin are reportedly associated with liver fibrosis. We evaluated the usefulness of serum transferrin and alpha-1 antitrypsin as new liver fibrosis markers in patients with chronic hepatitis B. METHODS: The study included 293 patients with chronic hepatitis B who underwent a liver biopsy between October 2005 and June 2009, and who had no history of hepatocellular carcinoma. Serum markers and liver fibrosis stages were compared. RESULTS: Univariate analysis revealed that age (P<0.001), serum platelet count (P<0.001), and serum alkaline phosphatase level (P=0.003) differed significantly between the patients with and without liver cirrhosis. Serum transferrin levels were significantly lower in advanced fibrosis than in mild fibrosis in both univariate analysis (P=0.002) and multivariate analysis (P=0.009). In addition, the serum transferrin level was significantly lower in cirrhotic patients than in noncirrhotic patients (P=0.020). However, the serum level of alpha-1 antitrypsin was not significantly associated with liver cirrhosis in patients with chronic hepatitis B. CONCLUSIONS: Serum transferrin could be promising serum marker for predicting advanced liver fibrosis in patients with chronic hepatitis B.

Validation and development of an immunonephelometric assay for the determination of alpha-1 antitrypsin levels in dried blood spots from patients with COPD / Desenvolvimento e validação de um método de imunonefelometria em amostras de sangue em papel-filtro para a dosagem da alfa-1 antitripsina em pacientes com DPOC

OBJECTIVE: To validate and develop an immunonephelometric assay for the determination of alpha-1 antitrypsin (AAT) levels in dried blood spots from COPD patients in Brazil. METHODS: We determined AAT levels in serum samples and dried blood spots from 192 COPD patients. For the preparation of dried blood spots, a disk (diameter, 6 mm) was placed into a tube, eluted with 200 µL of PBS, and stored overnight at 4ºC. All of the samples were analyzed by immunonephelometry in duplicate. We used the bootstrap resampling method in order to determine a cut-off point for AAT levels in dried blood spots. RESULTS: The correlation coefficient between the AAT levels in serum samples and those in dried blood spots was r = 0.45. For dried blood spots, the cut-off value was 2.02 mg/dL (97% CI: 1.45-2.64 mg/dL), with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 95.7%, 27.2%, and 100%, respectively. CONCLUSIONS: This method for the determination of AAT levels in dried blood spots appears to be a reliable screening tool for patients with AAT deficiency. .

OBJETIVO: Validar e desenvolver um método de dosagem de alfa-1 antitripsina (AAT) por imunonefelometria em amostras de sangue em papel-filtro em pacientes com DPOC no Brasil. MÉTODOS: Amostras de soro e de sangue em papel-filtro de 192 pacientes com DPOC foram utilizadas para a dosagem de AAT. Para a preparação das amostras de sangue em papel-filtro, um disco do papel com diâmetro de 6 mm foi colocado em um tubo e eluído com 200 µL de PBS, permanecendo por toda a noite a 4ºC. Todas as amostras foram analisadas em duplicata por imunonefelometria. O método de reamostragem bootstrap foi utilizado para a determinação de um ponto de corte para o nível de AAT nas amostras de sangue em papel-filtro. RESULTADOS: O coeficiente de correlação entre os níveis de AAT em soro e em sangue em papel-filtro foi de r = 0,45. Para as amostras em papel-filtro, o ponto de corte foi de 2,02 mg/dL (IC97%: 1,45-2,64 mg/dL), com sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo de 100%, 95,7%, 27,2% e 100%, respectivamente. CONCLUSÕES: Este método de determinação dos níveis de AAT em sangue em papel-filtro se mostrou uma ferramenta confiável para o rastreamento de pacientes com deficiência de AAT. .

Acquired alpha 1-antitrypsin deficiency in tropical pulmonary eosinophilia.

Background & objectives: Observation of an increased frequency of an intermediate deficiency of serum alpha1-antitrypsin (α1-AT) in patients with Tropical Pulmonary Eosinophilia (TPE) was earlier reported. Though the possibility of existence of an acquired deficiency was suggested, without phenotyping a hereditary α1-AT deficiency in TPE could not totally be ruled out. In this study, we have done Pi (Protease inhibitor) phenotyping to investigate the possibility of association of any heterozygous (or homozygous) α1-AT deficiency in patients with TPE. Methods: Serum a1antitrypsin (α1-AT) was measured in 103 patients (Group A) with TPE, 99 patients with pulmonary eosinophilia who had associated intestinal worm infestation (Group B) and 43 healthy volunteers who served as controls. In 19 α1-AT deficient patients (9 of Group A and 10 of Group B), α1-AT level was measured before and after treatment. In 58 patients with TPE and in 5 controls, phenotyping was done. Results: Fifteen patients of Group A and 16 from Group B showed intermediate α1-AT deficiency (150 mg % or less. None of the control subjects had α1-AT deficiency (<200 mg%). After treatment with DEC and/or deworming, in 19 patients there was a significant (P < 0.001) rise in α1-AT levels. Results of phenotyping showed that all had M1 or M2 allele and none had S or Z variant (either homozygous or heterozygous) thus ruling out any underlying genetic cause for the observed α1-AT deficiency. Interpretation & conclusions: The observed α1-AT deficiency may be due to the chronic inflammation in TPE and associated oxidative stress. However, in such α1-AT deficient patients with TPE and those with worm infested pulmonary eosinophilia, faecal α1-AT concentration and faecal α1-AT clearance should be routinely estimated to rule out the possibility of any intestinal protein loss.

Avaliação da concentração de alfa 1-antitripsina e da presença dos alelos S e Z em uma população de indivíduos sintomáticos respiratórios crônicos / Determination of alpha 1-antitrypsin levels and of the presence of S and Z alleles in a population of patients with chronic respiratory symptoms

OBJETIVO: Determinar a concentração de alfa 1-antitripsina (AAT) e a prevalência dos alelos S e Z em indivíduos sintomáticos respiratórios crônicos. MÉTODOS: Pacientes com tosse crônica e dispnéia foram submetidos à avaliação clínica, espirometria, tomografia computadorizada de tórax, dosagem de AAT por nefelometria e pesquisa das mutações S e Z por reação em cadeia da polimerase. Foram consideradas como variáveis dependentes a concentração de AAT e o tabagismo. RESULTADOS: Dos 89 pacientes incluídos no estudo (44 mulheres; idade média, 51,3 ± 18,2 anos), os alelos S e Z foram detectados em 33,3 por cento e 5,7 por cento, respectivamente, com freqüência gênica dos alelos S e Z de 0,16 e 0,028. Dois pacientes tinham genótipo SZ (AAT < 89 mg/dL). Os pacientes foram divididos em grupos segundo a concentração de AAT: < 89 mg/dL (deficiência, nenhum grupo); 90-140 mg/dL (faixa intermediária, Grupo 1, n = 30); e > 141 mg/dL (normal, Grupo 2, n = 57). A freqüência de fumantes foi igual nos dois grupos, com carga tabágica maior no Grupo 2. O alelo S estava presente em 13 e 14 pacientes dos Grupos 1 e 2, respectivamente, enquanto que o alelo Z estava presente em 2 e 1 paciente dos mesmos grupos. Não houve diferença nos testes de função pulmonar, nem na freqüência de bronquiectasias ou enfisema entre os dois grupos. Os valores espirométricos e as concentrações de AAT foram similares entre fumantes e não-fumantes. Bronquiectasias foram mais freqüentes entre os não fumantes, e enfisema foi mais freqüente entre os fumantes. CONCLUSÕES: Trinta pacientes apresentaram níveis de AAT abaixo da média esperada para os genótipos MM e MS, e este fato não pode ser explicado por uma freqüência maior dos alelos S e Z.

OBJECTIVE: To determine the levels of alpha-1 antitrypsin (AAT) and the presence of S and Z alleles in patients with chronic respiratory symptoms. METHODS: Patients with chronic cough and dyspnea were submitted to clinical evaluation, pulmonary function tests, high-resolution computed tomography, nephelometric determination of AAT and determination of S and Z alleles by polymerase chain reaction. Smoking and AAT levels were considered the dependent variables. RESULTS: Of the 89 patients included in the study, 44 were female. The mean age was 51.3 ± 18.2 years. The S and Z alleles were detected in 33.3 percent and 5.7 percent, respectively, and the gene frequency was 0.16 and 0.028, respectively. Two patients were SZ heterozygotes (AAT levels < 89 mg/dL). The patients were divided into groups based on AAT level: < 89 mg/dL (deficiency, no group); 90-140 mg/dL (intermediate, Group 1, n = 30); and > 141 mg/dL (normal, Group 2, n = 57). The frequency of smokers was the same in both groups, although tobacco intake was greater in Group 2. The S allele was present in 13 and 14 patients in Groups 1 and 2, respectively, whereas the Z allele was present in 2 and 1 patient in the same groups. There was no difference in the results of pulmonary function tests or in the frequency of bronchiectasis or emphysema between the two groups. Spirometric values and AAT levels were similar in smokers and nonsmokers. Bronchiectasis was more common in nonsmokers, and emphysema was more common in smokers. CONCLUSIONS: Thirty patients presented AAT levels lower than the mean values found in patients with the MM or MS genotype, and this fact could not be explained by an increased frequency of S and Z alleles.

Deficiência de alfa-1 antitripsina: diagnóstico e tratamento / Alpha-1 antitrypsin deficiency: diagnosis and treatment

A deficiência de alfa-1 antitripsina é um distúrbio genético de descoberta recente e que ocorre com freqüência comparável à da fibrose cística. Resulta de diferentes mutações no gene SERPINA1 e tem diversas implicações clínicas. A alfa-1 antitripsina é produzida principalmente no fígado e atua como uma antiprotease. Tem como principal função inativar a elastase neutrofílica, impedindo a ocorrência de dano tecidual. A mutação mais freqüentemente relacionada à doença clínica é o alelo Z, que determina polimerização e acúmulo dentro dos hepatócitos. O acúmulo e a conseqüente redução dos níveis séricos de alfa-1 antitripsina determinam, respectivamente, doença hepática e pulmonar, sendo que esta se manifesta principalmente sob a forma de enfisema de aparecimento precoce, habitualmente com predomínio basal. O diagnóstico envolve a detecção de níveis séricos reduzidos de alfa-1 antitripsina e a confirmação fenotípica. Além do tratamento usual para doença pulmonar obstrutiva crônica, existe atualmente uma terapia específica com infusão de concentrados de alfa-1 antitripsina. Essa terapia de reposição, aparentemente segura, ainda não teve a eficácia clínica definitivamente comprovada, e o custo-efetividade também é um tema controverso e ainda pouco abordado. Apesar da sua importância, não existem dados epidemiológicos brasileiros a respeito da prevalência da doença ou da freqüência de ocorrência dos alelos deficientes. O subdiagnóstico também tem sido uma importante limitação tanto para o estudo da doença quanto para o tratamento adequado dos pacientes. Espera-se que a criação do Registro Internacional de Alfa-1 venha a resolver essas e outras importantes questões.

Alpha-1 antitrypsin deficiency is a recently identified genetic disease that occurs almost as frequently as cystic fibrosis. It is caused by various mutations in the SERPINA1 gene, and has numerous clinical implications. Alpha-1 antitrypsin is mainly produced in the liver and acts as an antiprotease. Its principal function is to inactivate neutrophil elastase, preventing tissue damage. The mutation most commonly associated with the clinical disease is the Z allele, which causes polymerization and accumulation within hepatocytes. The accumulation of and the consequent reduction in the serum levels of alpha-1 antitrypsin cause, respectively, liver and lung disease, the latter occurring mainly as early emphysema, predominantly in the lung bases. Diagnosis involves detection of low serum levels of alpha-1 antitrypsin as well as phenotypic confirmation. In addition to the standard treatment of chronic obstructive pulmonary disease, specific therapy consisting of infusion of purified alpha-1 antitrypsin is currently available. The clinical efficacy of this therapy, which appears to be safe, has yet to be definitively established, and its cost-effectiveness is also a controversial issue that is rarely addressed. Despite its importance, in Brazil, there are no epidemiological data on the prevalence of the disease or the frequency of occurrence of deficiency alleles. Underdiagnosis has also been a significant limitation to the study of the disease as well as to appropriate treatment of patients. It is hoped that the creation of the Alpha One International Registry will resolve these and other important issues.

Interrelationship between serum and sputum inflammatory mediators in chronic obstructive pulmonary disease

Little is known about airway inflammatory markers in chronic obstructive pulmonary disease (COPD). The objective of the present study was to identify and try to correlate pulmonary and peripheral blood inflammatory markers in COPD. In a cross-sectional study on patients with stable COPD, induced sputum and blood samples were collected for the determination of C-reactive protein, eosinophilic cationic protein, serum amyloid A protein, a-1 antitrypsin (a-1AT), and neutrophil elastase. Twenty-two patients were divided into two groups according to post-bronchodilator forced expiratory volume in the first second ( percentFEV1): group 1 (N = 12, FEV1 <40 percent) and group 2 (N = 10, FEV1 ³40 percent). An increase in serum elastase, eosinophilic cationic protein and a-1AT was observed in serum markers in both groups. Cytology revealed the same total number of cells in groups 1 and 2. There was a significantly higher number of neutrophils in group 1 compared to group 2 (P < 0.05). No difference in eosinophils or macrophages was observed between groups. Serum elastase was positively correlated with serum a-1AT (group 1, r = 0.81, P < 0.002 and group 2, r = 0.83, P < 0.17) and negatively correlated with FEV1 (r = -0.85, P < 0.03 and -0.14, P < 0.85, respectively). The results indicate the presence of chronic and persistent pulmonary inflammation in stable patients with COPD. Induced sputum permitted the demonstration of the existence of a subpopulation of cells in which neutrophils predominated. The serum concentration of all inflammatory markers did not correlate with the pulmonary functional impairment.

Alpha-1 Antitrypsin and human tumour necrosis factor-alpha in Egyptian patients with fever

Serum alpha-1-antitrypsin and human tumor necrosis factor- alpha [IFN- alpha] were estimated in 20 cases with simple typhoid fever, 20 cases with complicated typhoid fever and 20 normal healthy individual. It was concluded that serum alpha-1-AT and TNF-alpha concentrations showed highly significant changes during febrile period of simple and complicated typhoid fevers and began to decline towards the base control after therapy and convalescence. So, alpha-1-AT and TNF-alpha measurements in typhoid fever were useful detectable parameters in differentiating between simple and complicated groups. Serum alpha-1-AT and TNF-alpha estimations were good markers of early manifestations of recovery and response to treatment in typhoid fever

Assessment of liver dysfunction in silica exposed workers

Seventy five silica exposed workers in sandbricks industry and twenty five controls were chosen for this study. Each individual was subjected to a questionnaire [for personal and medical histories] and clinical examination. Liver function tests, procollagen III peptide, alpha-I - antitrypsin, hepatitis markers [B and C], haematological tests for schistosomiasis, urine and stool analysis, abdominal sonography and chest X-ray were done for all chosen subjects. Environmental study was done for estimation of total and free crystalline silica. The results of environmental study showed higher concentration of total respirable dust and free crystalline silica than threshold limit values. Silica exposed workers had a significantly higher mean of gamma-glutamyl trans peptidase and procollagen III peptide than controls. These two parameters increased significantly in exposed workers [free from schistosomiasis and / or hepatitis markers] as chest grading of silicosis and time intensity factor increased. Gamma-glutamyl-trans peptidase and procollagen III peptide can be used for early detection of liver dysfunction in silica exposed workers. Also, in the pre-employment medical examination, individuals with previous liver affection [either due to schistosomiasis and / or hepatitis] should not be exposed to silica to avoid further deterioration of liver function

Valoración de la alfa-1-antitripsina en pacientes enfisematosos / Appraisement of alpha-1-antitrypsin in enphysematous patients

Se estudiaron prospectivamente 20 pacientes enfisematosos, cuyos diagnósticos fueron corroborados por exámenes clínicos, radiográficos y pruebas funcionales respiratorias. Se les dosificó alfa-1-antitripsina sérica y se correlacionaron con la electroforesis de proteínas. Se exponen los principales aspectos patogénicos del enfisema pulmonar. Se encontraron niveles elevados de alfa-1-antitripsina, lo que se interpretó como consecuencia del hábito de fumar y las infecciones broncopulmonares coadyuvantes

Consideraçöes a respeito da paracoccidioidomicose e sua correlaçäo com níveis séricos de alfa-1-antitripsina / Paracoccidioidomycosis and its correlation with serum alpha-1-antitrypsin

Foi utilizado no Hospital das Clínicas da UNICAMP, um estudo em 43 pacientes com paracoccidioidomicose, inicialmente sob o ponto de vista clínico, analizados pela procedência, profissäo, sexo, raça, tabagismo, etilismo, depois submetidos a colheita de sangue para a feitura de hemograma, velocidade de hemossedimentaçäo, electroforese de proteinas, dosagem de alfa-1 - AT e exames radiográficos de tórax. Com esses dados os pacientes foram separados em grupos de doença: Pulmonar, extra-pulmonar e mista. Estudando os resultados, verificou-se que a Forma Pulmonar realmente ocorreu mais no sexo masculino e raça caucasóide, enquanto que as outras formas ocorreram proporcionalmente mais no sexo feminino e raça negróide

Determinaçäo de alfa-1-antipripsina em pacientes neoplásicos e em casos de deficiência genética pelo método de Wenger e Sundy Modificado / Alpha-1-antitrypsin determination in patients witr neoplasms and Sundy's in cases of genetic deficiency by the Wenger's and Sundy's modified methods

Foram determinados os níveis de alfa-antitripsina sérica em 20 indivíduos pertencentes a três famílias com caso de deficiência genética de alfa-1-antitripssina. Os resultados variaram de 76 a 170 mg% de alfa-1-antitripsina. A mesma determinaçäo em 24 pacientes neoplásticos variou de 407 a 980 mg% de alfa-1-antitripsina. O valor normal do método insere-se na faixa de 306 ñ 55 mg% de alfa-1-antitripsina

Protein losing enteropathy in measles

Serum and faecal alpha-1 antitrypsin concentration as well as alpha-1 antitrypsin clearance were measured in 10 malnourished children with measles, 10 well nourished children with measles, as well as 10 age matched normal Egyption children. Serum alpha 1-antitrypsin concentrations were significantly lower than normal in both groups of measles. The intestinal clearance of alpha-1 antitrypsin was significantly high in the malnourished group. The dual effect of measles [usually sever in PEM] and mal-nutrition on the intestinal mucosa makes it more permeable to plasma proteins

Alpha-1-antitrypsin in leprosy.

Estimation of Alpha-1-antitrypsin (AAT) levels was carried out in 52 patients of various types of leprosy. Fifty age and sex matched healthy individuals served as controls. The mean level of AAT in controls was 290.12 +/- 59.56 mg/dl. In patients of tuberculoid leprosy (TT), borderline tuberculoid leprosy (BT) and borderline leprosy (BB), the AAT levels were found to be 284 +/- 47.03, 314.37 +/- 31.56 and 324.44 +/- 32.05 mg/dl respectively. These were statistically insignificantly raised when compared with controls. In borderline lepromatous leprosy (BL), lepromatous leprosy without erythema nodosum leprosum (LL without ENL) and in LL with ENL there was a statistically significant rise in AAT levels. The maximum levels of AAT were observed in patients of LL with ENL (mean 500.8 +/- 93.44 mg/dl. P less than 0.001).

Estudios inmunohistoquímicos en hepatocarcinomas / Immunohistochemical studies in hepatocarcinomas

Se estudiaron 18 hepatocarcinomas en los que se investigó mediante el método de peroxidasa-antiperoxiadasa la presencia de alfa-1-antitripsina (A1AT), alfa feto proteína (AFP) y el antígeno de superficie de la hepatitis B (HBsAg) en el tejido tumoral y del parénquima hepático no neoplásico. Se halló positividad para A1AT en 13 casos (72 por ciento), siendo la tinción citoplasmática de tipo globular o difusa. La AFP fue positiva en 4 casos (22%) en forma globular. Todos los casos positivos para AFP lo fueron también para A1AT. La presencia de HBsAg fue detectada en dos casos (11%) en el citoplasma de las células tumorales. De los 8 casos en que contaba con parénquima hepático no neoplásico, en 2 se observó positividad difusa para A1AT. Este trabajo demuestra la alta frecuencia de positividad de A1AT en carcinomas hepatocelulares. Si bien no se trata de un marcador tumoral específico es de ayuda diagnóstica en un tumor histológicamente compatible con esta neoplasia. La AFP es mucho más específica aunque la frecuencia con que fue hallada es mucho menor. La positividad para HBsAg es un dato más sobre la posible vinculación etiológica entre el virus de la hepatitis B y el desarrollo de estos tumores

Serum alpha-1 antichymotrypsin is a possible growth inhibitor of Plasmodium falciparum.

Serum protease inhibitors were determined in paired sera from 7 patients with cerebral malaria and 2 patients with acute malaria showing high and low growth inhibition activity in the initial and follow-up sera respectively. Alpha-1 antichymotrypsin and alpha-1 antitrypsin but not alpha-2 macroglobulin showed direct correlation with the growth inhibition activity. When alpha-1 antitrypsin was deliberately added to the malarial culture no growth inhibition occurred indicating that the alpha-1 antichymotrypsin was the most likely factor responsible for inhibition of growth of malarial parasites in vitro.