Power-series solution of compartmental epidemiological models.

In this work, power-series solutions of compartmental epidemiological models are used to provide alternate methods to solve the corresponding systems of nonlinear differential equations. A simple and classical SIR compartmental model is considered to reveal clearly the idea of our approach. Moreover, a SAIRP compartmental model is also analyzed by using the same methodology, previously applied to the COVID-19 pandemic. Numerical experiments are performed to show the accuracy of this approach.

Representation of [Formula: see text]-Bernstein polynomials in terms of [Formula: see text]-Jacobi polynomials.

A representation of [Formula: see text]-Bernstein polynomials in terms of [Formula: see text]-Jacobi polynomials is obtained.

Unsteady non-Newtonian blood flow through a tapered overlapping stenosed catheterized vessel.

The unsteady flow characteristics of blood in a catheterized overlapping stenosed artery are analyzed in presence of body acceleration and magnetic field. The stenosed arterial segment is modeled as a rigid constricted tube. An improved shape of stenosis in the realm of the formulation of the arterial narrowing caused by atheroma is integrated in the present study. The catheter inside the artery is approximated by a thin rigid tube of small radius while the streaming blood in the artery is characterized by the Carreau model. Employing mild stenosis condition, the governing equation of the flow is derived which is then solving numerically using finite difference scheme. The variation of axial velocity, flow rate, resistance impendence and wall shear stress is shown graphically for various parameters of interest. The flow patterns illustrating the global behavior of blood are also presented.

Induction of labour and the mode of delivery at term.

This is a retrospective cohort study to establish the effect of induction of labour (IOL) on the mode of delivery for term pregnancy. Studied population included 11,660 deliveries and out of these, 8,314 were normal vaginal deliveries; 1,775 instrumental deliveries and 1,571 emergency caesarean sections. The frequency of IOL was 23.6%. A univariate analysis was carried out to establish a relationship between IOL and mode of delivery. The multivariable regression analysis was carried out to adjust this relationship for parity, age, gestational age, epidural analgesia and birth weight. IOL at term lowered the risk of instrumental delivery (p=0.009) and had no influence on the rate of caesarean section (p=0.861). Hence, the study demonstrates that women in whom induction is decided upon, the instrumental delivery and caesarean section rate is not any higher than in the group where a spontaneous labour is awaited.

Predicting the risk of endometrial cancer in postmenopausal women presenting with vaginal bleeding: the Norwich DEFAB risk assessment tool.

BACKGROUND: This study aimed to show the longitudinal use of routinely collected clinical data from history and ultrasound evaluation of the endometrium in developing an algorithm to predict the risk of endometrial carcinoma for postmenopausal women presenting with vaginal bleeding. METHODS: This prospective study collected data from 3047 women presenting with postmenopausal bleeding. Data regarding the presence of risk factors for endometrial cancer was collected and univariate and multivariate analyses were performed. RESULTS: Age distribution ranged from 35 to 97 years with a median of 59 years. A total of 149 women (5% of total) were diagnosed with endometrial carcinoma. Women in the endometrial cancer group were significantly more likely to be older, have higher BMI, recurrent episodes of bleeding, diabetes, hypertension, or a previous history of breast cancer. An investigator best model selection approach was used to select the best predictors of cancer, and using logistic regression analysis we created a model, 'Norwich DEFAB', which is a clinical prediction rule for endometrial cancer. The calculated Norwich DEFAB score can vary from a value of 0 to 9. A Norwich DEFAB value equal to or greater than 3 has a positive predictive value (PPV) of 7.78% and negative predictive value (NPV) of 98.2%, whereas a score equal to or greater than 5 has a PPV of 11.9% and NPV of 97.8%. CONCLUSION: The combination of clinical information with our investigation tool for women with postmenopausal vaginal bleeding allows the clinician to calculate a predicted risk of endometrial malignancy and prioritise subsequent clinical investigations.

Recurrent endometriosis following total hysterectomy with oophorectomy mimicking a malignant neoplastic lesion: a diagnostic and therapeutic challenge.

CASE REPORT: A woman with a previous hysterectomy and bilateral salpingo-oophorectomy for endometriosis presented with painless vaginal bleeding. Imaging revealed a heterogeneous soft tissue pelvic mass suggestive of a malignant neoplastic lesion. Radical surgery was performed including excision of the pelvic mass and anterior resection of the sigmoid colon. Histopathology revealed endometriosis. CONCLUSION: The risk of malignant transformation and the difficulty in achieving a preoperative diagnosis make radical surgery inevitable in the management of recurrent endometriosis. The use of hormone replacement therapy after bilateral salpingo-oophorectomy for endometriosis remains controversial and requires careful counseling about recurrence and close follow-up.

Use of fuzzy clustering technique and matrices to classify amino acids and its impact to Chou's pseudo amino acid composition.

In this paper we present a study of classification of the 20 amino acids via a fuzzy clustering technique. In order to calculate distances among the various elements we employ two different distance functions: the Minkowski distance function and the NTV metric. In the clustering procedure we take into account several physical properties of the amino acids. We examine the effect of the number and nature of properties taken into account to the clustering procedure as a function of the degree of similarity and the distance function used. It turns out that one should use the properties that determine in the more important way the behavior of the amino acids and that the use of the appropriate metric can help in defining the separation into groups.

Ectoines as compatible solutes and carbon and energy sources for the halophilic bacterium Chromohalobacter salexigens.

AIMS: To investigate the catabolism of ectoine and hydroxyectoine, which are the major compatible solutes synthesized by Chromohalobacter salexigens. METHODS AND RESULTS: Growth curves performed in M63 minimal medium with low (0.75 mol l(-1) NaCl), optimal (1.5 mol l(-1) NaCl) or high (2.5 mol l(-1) NaCl) salinity revealed that betaine and ectoines were used as substrate for growth at optimal and high salt. Ectoine transport was maximal at optimal salinity, and showed 3- and 1.5-fold lower values at low and high salinity respectively. The salt-sensitive ectA mutant CHR62 showed an ectoine transport rate 6.8-fold higher than that of the wild type. Incubation of C. salexigens in a mixture of glucose and ectoine resulted in a biphasic growth pattern. However, CO(2) production due to ectoine catabolism was lower, but not completely abolished, in the presence of glucose. When used as the sole carbon source, glycine betaine effectively inhibited ectoine and hydroxyectoine synthesis at any salinity. CONCLUSIONS: The catabolic pathways for ectoine and hydroxyectoine in C. salexigens operate at optimal and high (although less efficiently) salinity. Endogenous ectoine(s) may repress its own transport. Ectoine utilization was only partially repressed by glucose. Betaine, when used as carbon source, suppresses synthesis of ectoines even under high osmolarity conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is a previous step to the subsequent isolation and manipulation of the catabolic genes, so as to generate strains with enhanced production of ectoine and hydroxyectoine.

Cell cycle and apoptotic proteins in relation to ovarian epithelial morphology.

OBJECTIVE: To assess the relationship between the expression of cell cycle and apoptotic proteins and the morphological appearance of the surface epithelium in non-neoplastic ovaries. METHODS: The subjects for this study were 79 women who had undergone oophorectomy for benign conditions at the North Middlesex Hospital, London, and Royal Free Hospital, London, and whose ovaries had been reported on routine histology as entirely normal or containing physiological cysts or endometriosis. The epithelial morphology was reassessed on haematoxylin and eosin-stained paraffin wax sections using nine cytological and architectural parameters associated with premalignant intraepithelial changes. A 'score' was obtained for each ovary. Expression of p53, Ki67, cyclin D1 and Bcl-2 in the surface, cystic and endometriotic epithelium was assessed in corresponding sections using standard immunohistochemistry. RESULTS: The median score for the morphological changes was significantly higher in the sections, which expressed p53 compared to those which did not. This difference remained significant in a subanalysis of the sections, which did not contain endometriosis. No relationship was identified between the morphological score and the expression of Ki67, Bcl-2 and cyclin D1. CONCLUSION: Increased intraepithelial abnormality as assessed by an epithelial morphological score of ovarian sections is associated with expression of the p53 cell cycle protein. This lends credence to the hypothesis that the ovarian surface or cystic epithelium goes through an identifiable precursor or "premalignant" phase before the development of invasive disease. Further work is required to characterise the changes that take place before the development of malignancy in ovarian epithelium.

Is there a link between vulval cancer and blood group?

Risk factors for squamous cell vulval cancer (SCC) remain unclear though there have been associations with lichen sclerosis, smoking, and vulval intraepithelial neoplasia (VIN). We studied 191 patients who had been referred to the vulval clinic at the Royal Free Hospital and who had both blood group and histopathology results available. Seventy-two percent of patients with SCC and non-neoplastic epithelial disorders of the vulva (NNEDV) were found to be in blood group A with only 17% in blood group O. Those with SCC associated with VIN had only 30% in blood group A with 50% in blood group O. The control population showed that 38% of the population were in blood group A and 43% were in blood group O. Our results suggest that blood group A is prevalent in patients with SCC associated with NNEDV but not in those women with squamous vulval cancer and associated VIN.

Ovarian epithelial dysplasia in relation to ovulation induction and nulliparity.

OBJECTIVE: The goal of this study was to assess the relationship between ovulation induction, nulliparity, and ovarian epithelial dysplasia. METHODS: This retrospective cohort study was performed in one teaching and one district general hospital in London. The subjects, 83 women who had undergone hysterectomy and bilateral oophorectomy and whose ovaries were reported as "normal," were divided into three groups: ovulation induction (13), nulliparity (20), and fertile controls (50). These ovaries were independently reviewed by two pathologists who assigned a score of 0, 1, or 2 to nine epithelial cytological and architectural features. The main outcome measure was the total dysplasia score, which was used to quantify the degree of ovarian epithelial abnormality in the three groups. RESULTS: The mean dysplasia score was significantly higher in the women who had undergone ovulation induction than in the fertile controls (7.92 vs 5.70, P = 0.012). The magnitude of the difference between the ovulation induction group and controls remained similar after adjusting for age, parity, and duration of oral contraceptive use (2.17, 95% CI: -0.11-4.44). However, the statistical significance of this difference was reduced (P = 0.062). We did not find any evidence of a difference in dysplasia score between nulliparous women and controls, neither before (P = 0.85) nor after adjusting for age and duration of oral contraceptive use (P = 0.87). CONCLUSIONS: These results suggest a possible association between ovarian epithelial dysplasia and ovulation induction therapy, in accord with previous reports of increased risk of ovarian cancer in women with a history of fertility treatment. The higher dysplasia score could be attributable to the drugs used to induce ovulation or to a genetic susceptibility to ovarian cancer.

Chromohalobacter salexigens sp. nov., a moderately halophilic species that includes Halomonas elongata DSM 3043 and ATCC 33174.

Two strains that were originally isolated and characterized as members of the moderately halophilic species Halomonas elongata, strains DSM 3043 (= 1H11) and ATCC 33174 (= 1H15), were studied in detail. Their complete 16S rRNA sequences were determined and, when compared to sequences available from the databases, they showed a close phylogenetic relationship to Chromohalobacter marismortui. In addition, DNA-DNA hybridization experiments showed that both strains are members of the same species, but their DNA relatedness to the type strains of Halomonas elongata, ATCC 33173T, and Chromohalobacter marismortui, ATCC 17056T, is very low. Phenotypically, the two strains showed very similar features, related to those of Chromohalobacter, but clear differences were found between these two strains and Chromohalobacter marismortui. On the basis of these data, it is proposed that Halomonas elongata DSM 3043 and ATCC 33174 should be included in a new species of the genus Chromohalobacter, Chromohalobacter salexigens sp. nov. The type strain is DSM 3043T (= ATCC BAA-138T = CECT 5384T = CCM4921T = CIP106854T = NCIMB 13768T).

Release of cell-free ice nuclei from Halomonas elongata expressing the ice nucleation gene inaZ of Pseudomonas syringae.

Release of ice nuclei in the growth medium of recombinant Halomonas elongata cells expressing the inaZ gene of Pseudomonas syringae was studied in an attempt to produce cell-free active ice nuclei for biotechnological applications. Cell-free ice nuclei were not retained by cellulose acetate filters of 0.2 microm pore size. Highest activity of cell-free ice nuclei was obtained when cells were grown in low salinity (0.5-5% NaCl, w/v). Freezing temperature threshold, estimated to be below -7 degrees C indicating class C nuclei, was not affected by medium salinity. Their density, as estimated by Percoll density centrifugation, was 1.018 +/- 0.002 gml(-1) and they were found to be free of lipids. Ice nuclei are released in the growth medium of recombinant H. elongata cells probably because of inefficient anchoring of the ice-nucleation protein aggregates in the outer membrane. The ice+ recombinant H. elongata cells could be useful for future use as a source of active cell-free ice nucleation protein.

A nonlinear biomathematical model for the study of intracranial aneurysms.

The formation and rupture of aneurysms is a significant medical problem, but is not clearly understood. Most intracranial aneurysm are located in the circle of Willis. We consider a nonlinear mathematical model that simulates the blood flow inside the aneurysm, one of the relevant factors in the evolution of an aneurysm. Different techniques from nonlinear analysis are used in order to obtain, from the model, several consequences that would help to understand some medical aspects of aneurysms of the circle of Willis.

Cloning and expression of alpha-amylase from the hyperthermophilic archaeon Pyrococcus woesei in the moderately halophilic bacterium Halomonas elongata.

An extracellular alpha-amylase gene from the hyperthermophilic archaeon Pyrococcus woesei has been cloned and sequenced. The 1.4-kb protein-coding sequence is identical to that of the corresponding alpha-amylase gene of the closely related species P. furiosus. By using a shuttle cloning vector for halophilic bacteria, the P. woesei alpha-amylase was expressed in the moderate halophile Halomonas elongata, under the control of a native H. elongata promoter. The hyperthermophilic amylase activity expressed in the halophilic host was recovered completely in the crude membrane fraction of cell homogenates, suggesting the formation of inclusion bodies or that the secretion machinery of H. elongata may fail to recognize and release the pyrococcal alpha-amylase to the extracellular medium. However, thermal stability, metal ion interactions, optimal temperature and pH values for the crude and purified recombinant alpha-amylase were comparable with those of the native pyrococcal enzyme. The P. woesei amylase activity expressed in H. elongata was consistently detected in the cells upon growth on a wide range of NaCl concentrations (0.7-2.5 mol l-1). To our knowledge, this is the first report on the expression of an archaeal gene (P. woesei alpha-amylase) in a moderate halophilic host which serves as a cell factory able to grow under extreme salt conditions and with very simple nutritional requirements.

Lipid effects of hormone replacement therapy with sequential transdermal 17-beta-estradiol and oral dydrogesterone.

OBJECTIVE: To assess the effects on lipid and lipoprotein levels of a combination therapy of matrix patch and oral sequential dydrogesterone. METHODS: The lipid effects of transdermal estradiol (E2) (80 microg/day continuously) and oral dydrogesterone (10 mg from days 15-28 of each cycle) were assessed in a multicenter, prospective, open, baseline-controlled study. Subjects were 42 healthy, postmenopausal women who had not had hysterectomies. Fasting blood samples were taken at baseline, day 14 of cycle 3 (estrogen alone), and day 25 of cycle 6 (estrogen and progestogen). The main outcome measures were changes from baseline in total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides after six cycles. RESULTS: Thirty-six subjects completed six cycles and in the 28 with complete data, HDL cholesterol increased by 10.6% from 65.25 to 72.2 mg/dL (95% confidence interval [CI] 2.32, 11.58, P = .005) and LDL cholesterol fell by 5.1% from 130.9 to 124.3 mg/dL (95% CI 13.9, 1.16, P = .07). There was a nonsignificant decrease in LDL cholesterol from 130.9 at baseline to 124.3 mg/dL at 6 months and in triglycerides from 110.6 to 107.1 mg/dL. CONCLUSION: Sequential treatment with transdermal E2 and oral dydrogesterone increased HDL cholesterol, without the accompanying increase in triglycerides that occurs with oral estrogen replacement therapy.