Flexibility vs Preorganization: Direct Comparison of Binding Kinetics for a Disordered Peptide and Its Exact Preorganized Analogues.

Many intrinsically disordered proteins, which are prevalent in nature, fold only upon binding their structured partner proteins. Such proteins have been hypothesized to have a kinetic advantage over their folded, preorganized analogues in binding their partner proteins. Here we determined the effects of ligand preorganization on the kon for a biomedically important system: an intrinsically disordered p53 peptide ligand and the MDM2 protein receptor. Based on direct simulations of binding pathways, computed kon values for fully disordered and preorganized p53 peptide analogues were within error of each other, indicating little if any kinetic advantage to being disordered or preorganized for binding the MDM2 protein. We also examined the effects of increasing the concentration of MDM2 on the extent to which its mechanism of binding to the p53 peptide is induced fit vs conformational selection. Results predict that the mechanism is solely induced fit if the unfolded state of the peptide is more stable than its folded state; otherwise, the mechanism shifts from being dominated by conformational selection at low MDM2 concentration to induced fit at high MDM2 concentration. Taken together, our results are relevant to any protein binding process that involves a disordered peptide of a similar length that forms a single α-helix upon binding a partner protein. Such disorder-to-helix transitions are common among protein interactions of disordered proteins and are therefore of fundamental biological interest.

Treatment with cucurbitacin B alone and in combination with gefitinib induces cell cycle inhibition and apoptosis via EGFR and JAK/STAT pathway in human colorectal cancer cell lines.

The epidermal growth factor receptor (EGFR) associated with signaling pathways, such as Janus kinase (JAK)/signal transducer and activator of transcription (STAT), plays an important role in colorectal cancers (CRCs). Gefitinib (Gef) is an orally active inhibitor targeting the adenosine tri phosphate-binding domain of EGFR, and cucurbitacin B (CuB) is a selective inhibitor of JAK/STAT signaling with potent antitumor activity via suppression of STAT3 phosphorylation, but the underlying mechanism is not clear. We aimed to investigate the apoptotic and antiproliferative effects of CuB as a single agent and in combination with Gef on both HT-29 and HCT-116 cell lines. Cell proliferation, cell cycle distribution, and apoptosis were evaluated using viability assay, fluorescent microscopy, cytotoxicity assay, proliferation, DNA fragmentation, and cleaved caspase 3 levels. Real-time polymerase chain reaction and Western blot analyses were performed to determine the expression of relevant genes and proteins including antiapoptotic, proapoptotic, and cell cycle regulation. EGFR, phosphorylated EGFR (pEGFR), STAT3, and pSTAT3 proteins were evalutaed with Western blot analysis. Our results showed that, compared to CuB alone, CuB plus Gef treatment caused a significant growth and cell cycle inhibition and induced apoptosis in both cell lines. Also CuB plus Gef treatment decreased DNA synthesis rate more effectively than CuB alone. Treatment with CuB alone and in combination with Gef decreased the expression levels of B-Cell CLL/Lymphoma 2 (Bcl-2), BCL2-like 1 (BCL2L1), cyclin D1, pSTAT3, and pEGFR and increased the expression levels of Bcl-2-like protein 4, Bcl-2 homologous antagonist/killer, Bcl-2-associated death promoter, Bcl-2-like protein 11, and p27kip1 levels. Our results suggest that treatment with CuB alone and more likely in combination with Gef may be a considerable alternative therapeutic approach for CRC, at least in vitro.

Effect of polyethylene glycol induced drought stress on photosynthesis in two chickpea genotypes with different drought tolerance.

Responses of parameters related with photosynthesis and the involvement of various factors in photosynthetic damage in two chickpea genotypes, Gokce (tolerant) and Kusmen (sensitive) under drought stress were assessed. Photosynthetic pigment content decreased under drought stress in two genotypes. Significant decreases in gs, Pn and E were determined in Kusmen. No significant change in these parameters was measured in Gokce under drought stress. Fv/Fm, ΦPS2 and ETR decreased in drought stressed plants of Kusmen as compared to control plants however Fv/Fm, ΦPS2 and ETR did not change in Gokce under drought stress. Increases in NPQ were determined under stress in both genotypes. Drought stress did not affect rubisco activity and rubisco concentration in Gokce while, the activity and the content declined in Kusmen. The drought tolerance of the Gokce genotype is a consequence of a balance among leaf water potential, stomatal conductance, photosynthesis, and transpiration. On the other hand, photosynthesis in Kusmen may be not only restricted by stomatal limitations but also by non-stomatal limitations under drought stress.

Effects of probiotics on experimental short-bowel syndrome.

BACKGROUND: This study was performed to analyze the potential benefits of probiotics on experimental short-bowel syndrome (SBS). METHODS: Forty-eight male Wistar-Albino rats were used in the study. The animals were divided into 6 groups as follows: control, rats that received probiotics, rats that underwent intestinal transection and anastomosis, rats that underwent anastomosis and received probiotics, rats that underwent 75% intestinal resection, and rats that underwent 75% intestinal resection plus received probiotics. Body weight monitoring, intestinal bowel diameter, villus length and crypt depth measurements, goblet cell count, mitosis, and immunohistochemical evaluation were used for the assessment of intestinal proliferation ability. RESULTS: Statistical analysis showed a significant difference in villus length, crypt depth, goblet cell count in villus and crypt, mitosis, and immunohistochemical evaluation in the jejunum when the SBS group was compared with the SBS group that received probiotics. There was no significant difference in these parameters in ileum. CONCLUSIONS: This trial clearly has shown that probiotics had a positive impact on jejunum in the experimental SBS.

The abdominal cocoon: a rare cause of intestinal obstruction.

The abdominal cocoon is a very rare entity leading to bowel obstruction. A 30-year-old man was admitted to the emergency department with symptoms and signs of mechanical intestinal obstruction. In addition to these, the recurrent episodes of obstruction in the patient's history and palpable abdominal mass found during the physical examination, appeared as important clinical characteristics of the pathology. A CT scan of the abdomen showed a conglomerate of bowel loops encased in a membrane. A Cocoon-like mass consisting of encapsulated bowel loops was the main finding of surgical exploration. Dissection and excision of the encapsulating membrane and release of encased loops provided definitive treatment of this rare entity.

The comparison of heavyweight mesh and lightweight mesh in an incisional animal model.

PURPOSE: An incisional hernia may occur through the incision area following a surgical operation, through the trocar opening and even through drainage exit points. Various synthetic surgical meshes have recently been used for the surgical repair of incisional hernias. In this study, we analysed the burst strength forces of heavyweight mesh and lightweight mesh in an incisional animal model. METHODS: Following experimental formation of incisional hernias in 32 Wistar albino rats, they were divided into four groups. Polypropylene suture was used for closure of the abdominal incision in Group 1. In Groups 2, 3 and 4, polyester, polypropylene + polyglactin and polypropylene meshes, respectively, were fixed on the surface of the fascia after closing the defects in the rats. Polypropylene and polyester meshes are classified as heavy mesh. Light mesh is composed of a non-absorbable part (polypropylene) and an absorbable part (polyglactin), which will disappear 80 days after implantation. The rats were sacrificed at the end of the experiment. The pullout force of the fascia and meshes were recorded by use of a digital tension meter. RESULTS: The mean pullout forces for Groups 1, 2, 3 and 4 were found to be 123.4 +/- 13.3, 292.33 +/- 17.4, 281.66 +/- 16.3 and 310.60 +/- 26.1 N, respectively. CONCLUSION: At the end of the experiment, the polypropylene (25 g/cm(2)) present in the lightweight mesh was found to lose only a small percentage of the burst strength compared to the polypropylene (85 g/cm(2)) present in the heavyweight mesh.

Photosystem II functionality and antioxidant system changes during leaf rolling in post-stress emerging Ctenanthe setosa exposed to drought.

We studied the changes in antioxidant system and chlorophyll fluorescence parameters in post-stress emerging Ctenanthe setosa (Rosc.) Eichler (Marantaceae) plants (PSE plants) having reduced leaf area under drought stress causing leaf rolling and re-watering. PSE plants were compared to primary stressed plants (PS) in previous studies. The parameters were measured at different visual leaf rolling scores from 1 to 4 (1 is unrolled, 4 is tightly rolled and the others is intermediate form). Water potentials and stomatal conductance of leaves were gradually decreased during leaf rolling. Similarly, maximum quantum efficiency of open PS II center and quantum yield of PS II decreased during the rolling period. Non-photochemical quenching of chlorophyll fluorescence decreased at score 2 then increased while photochemical quenching did not change during leaf rolling. Electron transport rate decreased only at score 4 but approximately reached to score 1 level after re-watering. Superoxide dismutase activity was not constant at all leaf rolling scores. Ascorbate peroxidase, catalase and glutathione reductase activities generally tended to increase during leaf rolling. Lipid peroxidation and H 2 O 2 content increased at score 2 but decreased at the later scores. On the other hand, O 2 .- production increased during the rolling period. After re-watering of the plants having score 4 of leaf rolling, antioxidant enzyme activities were lower than those of score 1. Other physiological parameters also tended to reach the value of score 1. The results indicated that PSE plants gained drought tolerance by reducing leaf area effectively induced their antioxidant systems and protected the photosynthesis under drought stress similar to PS plants.

Lymphovascular invasion, as a prognostic marker in patients with invasive breast cancer.

PURPOSE: The markers of prognosis are used to predict the clinical course of disease and the outcome for patients with invasive breast cancer. Our aim is to investigate the relationship of peritumoural lymphovascular invasion (LVI) with well-known prognostic markers. PATIENTS AND METHODS: Eighty-one surgically treated patients with invasive breast cancer were evaluated in this study during a mean follow-up period of 46 months (12-72). The patient's age (menopausal status), tumour size, nuclear grade, axillary lymph node involvement, and hormone receptor status were determined as markers of the prognosis. The relationship of LVI with these markers was established. RESULTS: Except for menopausal status (p = 0.25) a close relationship was found between the presence of LVI and studied prognostic factors. LVI was positive in 29% of T1, 54% of T2 (p = 0.028) and 100% of T3 tumours (p = 0.002). The rate of LVI (+) has increased gradually as 0%, 38% and 77% (p = 0.001) with grades 1, 2 and 3 respectively. Positive LVI has been determined in 85% (p < 0.0001) and 73% (p = 0.0004) of oestrogen and progesterone receptor negative tumours respectively. LVI was present in 14% and 73% (p < 0.0001) of patients with negative and positive axilla respectively. Metastatic cancer caused mortality in seven patients of whom 86% had more than four involved axillary nodes, and 100% LVI (+). CONCLUSION: The high rate of positive LVI shows a close relationship with known markers of poor prognosis. The presence of LVI can predict a worse outcome for patients with invasive breast cancer. LVI may be used as an indicator of aggressive behaviour, metastatic ability (nodal and systemic) of the primary malignancy.

Breast carcinoma with three coexistant type of metaplasia: sarcomatoid, giant cell and squamous differantiation.

We report on a women with metaplastic carcinoma of the right breast. After diagnosis she had a simple mastectomy operation. Pathological investigations were carried out on mastectomy material. Immunohistochemical analyses were performed. Bizarre, malignant giant cells and diffuse inflammatory reactions were predominantly noted. Sarcomatous metaplasia and rare squamous metaplasia were also seen. There was not any area of classic intraductal, invasive ductal, lobular or papillary carcinoma. The patient is still alive and well for more than five years. This uncommon case is described and discussed, and the related literature is reviewed.

Effects of probiotics on the severity of experimental acute pancreatitis.

OBJECTIVE: This study was designed to evaluate the effects of probiotics on the severity of experimental acute pancreatitis. DESIGN: Experimental study. SETTING: Experiments were done in a laboratory at Haydarpasa Numune Teaching and Research Hospital. SUBJECTS: A total of 50 Wistar rats were randomly divided into five groups. INTERVENTIONS: Group 1 was control group. Group 2 received an intraperitoneal injection of a 20% solution in 0.15 mol/l NaCL. Group 3 was injected NaCL and fed with probiotics. Acute pancreatitis was induced in rats by intrperitoneal injection of L-Arginine in groups 4 and 5. The rats in group 5 were treated with probiotics. The pancreas was removed for histologic examination. Evaluation of the pathologic changes was done by a new combined histopathologic grading scale. RESULTS: The mean scores of fibrosis, acinar cell loss, oedema, parenchymal necrosis, mononuclear cells infiltration, polymorphonuclear leucocytes infiltration, ductal damage and atypical reactive regeneration in group 5 were significantly lower than group 4. CONCLUSIONS: We demonstrated that enteral feedings with added probiotics can reduce the severity of acute pancreatitis. SPONSORSHIP: None.

Fetal biometry: size and configuration of the third ventricle.

PURPOSE: To evaluate the normal configuration and size of the third ventricle in second and third trimester fetuses in a normal population, and to compare our values with those of previously published studies. MATERIAL AND METHODS: Evaluation of fetal third ventricular width and configuration was obtained by antenatal ultrasonography in 474 fetuses with gestational age between 12 weeks and term (mean 28 weeks). Percentiles for third ventricle width were estimated by combining separate fractional polynominal regression models fitted to the mean and standard deviation, assuming that the measurements had a normal distribution at each gestational age. Appearance of the third ventricle was correlated with each gestational age. RESULTS: The third ventricle could be visualized in 471 (99%) of 474 fetuses. The 97th percentile of the third ventricle in preterm fetuses was measured as 3.6 mm in size. The third ventricle was seen as a single echogenic line in 153 (32.4%) of 474 fetuses. Two-hundred-and-ninety-nine (61.5%) of all fetuses had parallel echogenic lines outlining a fluid-filled lumen. V-shaped third ventricular configuration was seen in only 28 (5.9%) of the fetuses. From 24 weeks to term, parallel echogenic lines were the most commonly (83.7% to 79.6%) encountered configuration for the third ventricle. CONCLUSION: The 97th percentile of the third ventricle in preterm fetuses was measured as 3.6 mm in size. In the early second trimester, 77% of the fetuses had a single echogenic line appearance on ultrasonography. As the brain and ventricular structures mature, a parallel echogenic line becomes the prominent ultrasonography appearance (>80% of fetuses) in third trimester healthy fetuses.

Uterine leiomyoma with prominent lymphoid infiltrate.

We present a case of a 35-year-old woman whose myomectomy specimen revealed a leiomyoma nodule diffusely infiltrated by lymphocytes which were shown to be clonal in nature. Lymphoid infiltration of leiomyomas is a rare occurrence, and this is the first case with molecular analysis.

Coexistence of lactating adenoma and invasive ductal adenocarcinoma of the breast in a pregnant woman.

A 36 year old pregnant woman was admitted to hospital complaining of an enlarging mass in her left breast. Histopathological examination of the mastectomy specimen revealed a high grade infiltrating ductal adenocarcinoma intermixed with a lactating adenoma. Lactating adenomas are rare entities but are the most common masses that occur during pregnancy. Although they are not thought to carry an increased risk of cancer there are two other case reports in the literature of a lactating adenoma associated with an infiltrating carcinoma. In this case, areas where the lactating adenoma and the infiltrating carcinoma were intermixed could be identified. This case could simply be a collision tumour, although the possibility of an invasive carcinoma arising within a lactating adenoma cannot be ruled out. Because of the relative lack of experience with lactating adenomas, the question of an increased association with carcinoma development remains unclear.

Isolated metastasis of malignant melanoma into follicular carcinoma of the thyroid gland.

A 38-yr-old woman with a history of malignant melanoma (MM) presented with a thyroidal nodule. Fine needle aspiration biopsy of the thyroid was consistent with metastatic MM. The patient underwent thyroidectomy: microscopic examination revealed a follicular carcinoma nodule harboring a focus of metastatic melanoma. On review of the fine needle aspiration biopsy specimen, the population of cells with more uniform nuclei with focal follicle formation, which initially was interpreted as cells originating from normal thyroid tissue, was seen to actually represent the follicular carcinoma component. Tumor-to-tumor metastasis is an interesting phenomenon and there are only few cases of MM metastasis to other tumors. MM metastasis into a neoplastic thyroid nodule is a very rare combination and may be explained because the nodule in question represents the most highly vascularized component of the thyroid.

The condylar asymmetry measurements in different skeletal patterns.

In the present study, condylar asymmetry measurements were investigated on the lateral cephalometric head radiographs and the panoramic radiographs of 72 subjects (36 males and 36 females), aged 12-16-years and having different skeletal patterns. The lateral cephalometric head radiographs were divided into three groups according to the ANB angle: ANB angles smaller than 1 degrees, between 1 degrees and 5 degrees, and larger than 5 degrees. In addition, each group was also divided into two subgroups according to sex. The effects on the ANB angle and sex on the condylar asymmetry measurement were investigated on the panoramic radiographs by means of variance analysis. It was observed that while condylar + ramus ratio measurement was affected by the change of ANB angle, the other measurements were not affected by it.

Analysis of Holdaway soft-tissue measurements in children between 9 and 12 years of age.

In this study, 43 lateral cephalometric radiographs from 20 boys and 23 girls subjects were used to determine the Holdaway soft tissue growth changes. Subjects with Class I occlusions, balanced skeletal profiles, normal growth and development, and no orthodontic treatment history were included in the investigation. The cephalometric measurements were carried out on the first and second radiographs of each subject, with an average interval of 5 years. The growth changes in both sexes were analysed separately. The changes resulting from growth and development were determined by a paired t-test. The results showed that all measurements were significant at various levels except for upper lip sulcus depth, subnasal-H line distance, and lower lip H distance in girls, and upper lip sulcus depth, subnasal-H line distance, H angle and lower lip H line distance in boys. The measurement differences were observed with a Student's t-test. No significant difference was found for any measurement except upper lip base thickness (P < 0.001) and upper lip thickness (P < 0.01). The following measurements during the observation period were statistically different: soft-tissue facial angle (P < 0.01 in girls, P < 0.05 boys), nose prominence (P < 0.001 in girls and boys), skeletal profile convexity (P < 0.001 in girls, P < 0.01 in boys), basic upper lip thickness (P < 0.001 in girls and boys), upper lip thickness (P < 0.05 in girls, P < 0.001 in boys), H angle (P < 0.001 in girls), lower lip sulcus depth (P < 0.001 in girls and boys), and soft-tissue chin thickness (P < 0.001 in girls, P < 0.001 in boys).

Laparoscopic treatment of liver hydatid cysts.

We report the laparoscopic use of a novel perforator-grinder-aspirator apparatus, specifically designed for the evacuation of hydatid cysts. Eleven hepatic hydatid cysts in six patients were treated by laparoscopic technique using this tool, which penetrates the cyst mainly by opening a hole in the cyst wall, grinds the particulate, and sucks it all out; classic surgical aspirators are almost always blocked by daughter cysts and laminated membranes. If the cyst is small, management of the cavity is achieved by simple drainage; otherwise, vacuum obliteration with the application of -250-mbar negative pressure may be necessary. High vacuum obliterates the cystic cavity by clinging to the opposing cyst walls. In the postoperative period, none of these patients had bile drainage. In the following 6 to 20 months period, computed tomography (CT) and ultrasound examinations revealed progressive decrease in the size of seven cysts and disappearance of the lesions in five cysts. We therefore conclude that laparoscopic treatment of hepatic hydatid cysts can be easily and effectively accomplished by using this novel instrument. Obliteration of the cystic cavity by high vacuum is a time-saving procedure that is easy to perform and that reduces or totally eliminates bile drainage.