Bifurcations and chaos control in a discrete Rosenzweig-Macarthur prey-predator model

In this paper, we explore the local dynamics, chaos, and bifurcations of a discrete Rosenzweig-Macarthur prey-predator model. More specifically, we explore local dynamical characteristics at equilibrium solutions of the discrete model. The existence of bifurcations at equilibrium solutions is also studied, and that at semitrivial and trivial equilibrium solutions, the model does not undergo flip bifurcation, but at positive equilibrium solutions, it undergoes flip and Neimark-Sacker bifurcations when parameters go through certain curves. Fold bifurcation does not exist at positive equilibrium, and we have studied these bifurcations by the center manifold theorem and bifurcation theory. We also studied chaos by the feedback control method. The theoretical results are confirmed numerically.

Discrete-time COVID-19 epidemic model with chaos, stability and bifurcation

In this paper, we explore local behavior at fixed points, chaos and bifurcations of a discrete COVID-19 epidemic model in the interior of R + 5 . It is explored that for all involved parametric values, COVID-19 model has boundary fixed point and also it has an interior fixed point under certain parametric condition(s). We have investigated local behavior at boundary and interior fixed points of COVID-19 model by linear stability theory. It is also explored the existence of possible bifurcations at respective fixed points, and proved that at boundary fixed point there exists no flip bifurcation but at interior fixed point it undergoes both flip and hopf bifurcations, and we have explored said bifurcations by explicit criterion. Moreover, chaos in COVID-19 model is also investigated by feedback control strategy. Finally, theoretical results are verified numerically.

Discrete-time COVID-19 epidemic model with bifurcation and control

The local dynamics with different topological classifications, bifurcation analysis and chaos control in a discrete-time COVID-19 epidemic model are investigated in the interior of $ \mathbb{R}_+^3 $. It is proved that discrete-time COVID-19 epidemic model has boundary equilibrium solution for all involved parameters, but it has an interior equilibrium solution under definite parametric condition. Then by linear stability theory, local dynamics with different topological classifications are investigated about boundary and interior equilibrium solutions of the discrete-time COVID-19 epidemic model. Further for the discrete-time COVID-19 epidemic model, existence of periodic points and convergence rate are also investigated. It is also investigated the existence of possible bifurcations about boundary and interior equilibrium solutions, and proved that there exists no flip bifurcation about boundary equilibrium solution. Moreover, it is proved that about interior equilibrium solution there exists hopf and flip bifurcations, and we have studied these bifurcations by utilizing explicit criterion. Next by feedback control strategy, chaos in the discrete COVID-19 epidemic model is also explored. Finally numerically verified theoretical results.

Subcritical Neimark–Sacker bifurcation and hybrid control in a discrete-time Phytoplankton–Zooplankton model

In this paper, we explore the local dynamical behavior with different topological classifications around fixed points, Neimark–Sacker bifurcation and hybrid control in the discrete-time Phytoplankton–Zooplankton model. More precisely, we have investigated the local dynamical behavior with different topological classifications around trivial, semitrivial and interior fixed points of the two-dimensional Phytoplankton–Zooplankton model, respectively. The existence of possible bifurcations around fixed points is also investigated, and it is proved that there exists no flip bifurcation around trivial and semitrivial fixed points but around interior fixed point, the model undergoes Neimark–Sacker bifurcation only. Moreover, hybrid control strategy is utilized for controlling Neimark–Sacker bifurcation in the Phytoplankton–Zooplankton model. Lastly, theoretical results are verified numerically.

A72 NON-INVASIVE PREDICTION OF ESOPHAGEAL VARICES BY TRANSIENT ELASTOGRAPHY AND PLATELET COUNT IN PATIENTS WITH HEPATITIS B AND ADVANCED CHRONIC LIVER DISEASE: VALIDATION OF BAVENO VI AND EXPANDED BAVENO VI CRITERIA

Background

Patients with compensated advanced chronic liver disease (cACLD) are at higher risk of developing complications from portal hypertension, including esophageal varices (EV). Baveno VI and expanded Baveno VI criteria, based on liver stiffness measurement (LSM) by transient elastography combined with platelet count, have been proposed to avoid unnecessary esophagogastroduodenoscopy (EGD) screening for large esophageal varices needing treatment (EVNT). This approach has not been validated in patients with chronic hepatitis B virus (HBV) infection, who have etiology-specific cut-off of LSM for liver fibrosis.

Aims

We aimed to validate the Baveno VI and expanded Baveno VI criteria for EVNT in HBV patients with cACLD.

Methods

We performed a retrospective analysis of HBV patients who underwent LSM in 2014–2020. Inclusion criteria were: a) diagnosis of cACLD, defined as LSM >9 kPa; b) availability of EGD and platelets within 1 year of LSM. Baveno VI (LSM <20 kPa and platelets >150,000) and expanded Baveno VI criteria (LSM <25 kPa and platelets >110,000) were tested for EGD sparing. Diagnostic performance of these criteria against gold standard (EGD) was computed and compared to patients with hepatitis C virus (HCV) infection and nonalcoholic steatohepatitis (NASH) etiologies, where these criteria have been widely validated. In these patients, the threshold for cACLD definition was >10 kPa.

Results

A total of 287 patients (mean age 56, 95% Child A) were included, comprising of 43 HBV (58% on antiviral therapy), 134 HCV and 110 NASH patients. The prevalence of any grade EV and EVNT was 25% and 8% in the whole cohort, with 19% and 5% in HBV patients, respectively. Table 1 reports diagnostic performance, spared EGD and missed EVNT according to non-invasive criteria and cACLD etiology. Both Baveno VI and expanded Baveno VI criteria performed well in patients with HBV-related cACLD. There was no significant difference on diagnostic performance of these non-invasive criteria across the cACLD etiologies.

Conclusions

These results support use of non-invasive criteria based on LSM and platelets to spare unnecessary EGD in patients with HBV and cACLD. Baveno VI and expanded Baveno VI criteria can improve resource utilization and avoid invasive testing in context of screening EGD for patients with HBV-related cACLD.

Funding Agencies

None

Discrete-time predator-prey model with flip bifurcation and chaos control

We explore the local dynamics, flip bifurcation, chaos control and existence of periodic point of the predator-prey model with Allee effect on the prey population in the interior of $\mathbb{R}^*{_+^2}$. Nu-merical simulations not only exhibit our results with the theoretical analysis but also show the complex dynamical behaviors, such as the period-2, 8, 11, 17, 20 and 22 orbits. Further, maximum Lyapunov exponents as well as fractal dimensions are also computed numerically to show the presence of chaotic behavior in the model under consideration.

Bifurcations and chaos control in a discrete-time biological model

In this paper, bifurcations and chaos control in a discrete-time Lotka–Volterra predator–prey model have been studied in quadrant-[Formula: see text]. It is shown that for all parametric values, model has boundary equilibria: [Formula: see text], and the unique positive equilibrium point: [Formula: see text] if [Formula: see text]. By Linearization method, we explored the local dynamics along with different topological classifications about equilibria. We also explored the boundedness of positive solution, global dynamics, and existence of prime-period and periodic points of the model. It is explored that flip bifurcation occurs about boundary equilibria: [Formula: see text], and also there exists a flip bifurcation when parameters of the discrete-time model vary in a small neighborhood of [Formula: see text]. Further, it is also explored that about [Formula: see text] the model undergoes a N–S bifurcation, and meanwhile a stable close invariant curves appears. From the perspective of biology, these curves imply that between predator and prey populations, there exist periodic or quasi-periodic oscillations. Some simulations are presented to illustrate not only main results but also reveals the complex dynamics such as the orbits of period-2,3,13,15,17 and 23. The Maximum Lyapunov exponents as well as fractal dimension are computed numerically to justify the chaotic behaviors in the model. Finally, feedback control method is applied to stabilize chaos existing in the model.

Restarting Thalidomide-Dexamethasone Regimen in a Post-Abortive Female with Multiple Myeloma: Effective Clinical Response Possible

Nowadays, the prevalence of Multiple Myeloma (MM) seems to have been increasing among young females. Here, we report that thalidomide is contraindicated in pregnant women diagnosed with MM and those desirous of subsequent pregnancy. In this case report, we compared the clinical response of Thalidomide-Dexamethasone therapy in a post-abortive woman with persistently elevated β-hCG levels due to retained products of conception, undergoing hysterectomy later. This case report underlines the clinical significance of age, the effect of Thalidomide-Dexamethasone therapy even after initial discontinuation and the response to high β-hCG levels.

Neglected orthopedic oncology--Causes, epidemiology and challenges for management in developing countries

BACKGROUND

Management of malignant bone and soft tissue tumors remains an overwhelming confront to orthopedic surgeons. The challenge is discriminating in developing countries due to inadequate diagnostic and therapeutic amenities and unawareness. A lot has been discussed about the neglected orthopedic trauma, but the published literature on the causes and management of neglected bone and soft tissue tumors is sparse. Hence, current study was undertaken to highlight the causes of neglect and therapeutic challenges for managing these neglected tumors in developing countries.

AIMS AND OBJECTIVES

To determine the causes of neglect of malignant bone and soft tissue tumors, their epidemiology (including their relative frequencies, age, gender discrimination, anatomical sites of occurrence and histological characteristics) and difficult aspect of management due to neglect or delayed presentation.

MATERIALS AND METHODS

This was an appraisal of the neglected malignant bone and soft tissue tumors presented to J. N. Medical College and Hospital from June 2008 to May 2013. Criteria for labeling the tumor as neglected malignant bone and soft tissue tumor was delayed presentation (>3 months), locally advanced disease, ulceration, sepsis, fungating mass or metastasis at the time of presentation. All the cases were reviewed and analyzed for age, gender, histological types, educational status and socioeconomic status of the family, any prior treatment by traditional bone setters or registered medical practitioner, cause of delay for seeking medical advice. We have also analyzed the treatment given at our institute and the outcome of the tumor.

OBSERVATIONS AND RESULTS

Eighteen patients fulfilled the criteria for neglected malignant bone and soft tissue tumors, hence were included in study. Eight cases were of osteosarcoma, five cases were of Ewing's sarcoma, three cases were of chondrosarcoma and 1 case each was of pleomorphic liposarcoma and primary lymphoma of bone. According to Enneking staging system 11 cases were of stage III (distant metastasis) and 7 were stage II-B. Seven were females, and 11 were males. Age range was 5-68 years. 15 patients (83.3%) belonged to low socioeconomic status with 17 patients (94.4%) belonged to uneducated background. Cause of delay in seeking medical advice was neglect by the patient and family due to financial constraints, cultural and religious believes, lack of access to health care facilities, consultation with traditional bone setters and even misdiagnosis by qualified orthopedic surgeons. The tumors included were all unresectable and of huge sizes, hence were managed with amputation/dis-articulation, chemotherapy or radiation.

CONCLUSION

The current study tries to highlight the causes and quantity of neglect of malignant bone and soft tissue tumors prevalent in our country, which poses a therapeutic challenge for management and consequent mutilating surgeries with poor outcome resulting in loss of extremity and existence.

Mitigation of 5-fluorouracil-induced liver damage in rats by vitamin C via targeting redox-sensitive transcription factors

Adverse complications associated with antineoplastic drug-based cancer therapy are the major clinical drawbacks. Oxidative stress and inflammation play a major role in the damage due to cancer therapy. In the current study, we investigated the modulatory effect of vitamin C (Vit. C) on liver toxicity induced by 5-fluorouracil (5-FU) in rats. Animals were divided into four groups. Animals in group I received vehicle. Oral gavage of Vit. C (500 mg kg^-1 body weight (b.wt.)) was given to the animals in group III and group IV. 5-FU (150 mg kg^-1 b.wt.) was injected intraperitoneally to the animals in group II and group III. Findings of the present study revealed that oral administration of Vit. C significantly ameliorated the level of lipid peroxidation and the activity of myeloperoxidase. Vit. C administration markedly reduced the activation of nuclear factor κB and expression of cyclooxygenase 2, whereas nuclear translocation of nuclear factor erythroid 2-related factor 2 was increased. Hepatic histopathological analyses further supported the protective effect of Vit. C. Findings of the current study demonstrate that the toxic free radicals and inflammatory mediators generated due to chemotherapy play a critical role in 5-FU-induced hepatic damage. Attenuating action of Vit. C may be due to the modulation of redox-sensitive transcription factors and associated target molecules.

Neimark-Sacker bifurcation of a two-dimensional discrete-time predator-prey model

In this paper, we study the dynamics and bifurcation of a two-dimensional discrete-time predator-prey model in the closed first quadrant \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb {R}_+^2$$\end{document}R+2. The existence and local stability of the unique positive equilibrium of the model are analyzed algebraically. It is shown that the model can undergo a Neimark-Sacker bifurcation in a small neighborhood of the unique positive equilibrium and an invariant circle will appear. Some numerical simulations are presented to illustrate our theocratical results and numerically it is shown that the unique positive equilibrium of the system is globally asymptotically stable.

Stability analysis of a discrete biological model

In this paper, we investigate the equilibrium point, local and global behavior of the unique positive equilibrium point, and rate of convergence of positive solutions of following discrete biological model: [Formula: see text] where parameters [Formula: see text] and the initial conditions [Formula: see text] are positive real numbers. Some numerical examples are given to verify theoretical results.

Trichloroethylene-mediated cytotoxicity in human epidermal keratinocytes is mediated by the rapid accumulation of intracellular calcium: Interception by naringenin

Industrial solvents pose a significant threat to the humankind. The mechanisms of their toxicity still remain in debate. Trichloroethylene (TCE) is a widespread industrial solvent responsible for severe liver dysfunction, cutaneous toxicity in occupationally exposed humans. We utilized an in vitro system of human epidermal keratinocyte (HaCaT) cells in this study to avoid complex cell and extracellular interactions. We report the cytotoxicity of organic solvent TCE in HaCaT and its reversal by a natural flavanone, naringenin (Nar). The cytotoxicity was attributed to the rapid intracellular free calcium (Ca(2+)) release, which might lead to the elevation of protein kinase C along with robust free radical generation, instability due to energy depletion, and sensitization of intracellular stress signal transducer nuclear factor κB. These effects were actually seen to induce significant amount of genomic DNA fragmentation. Furthermore, all these effects of TCE were effectively reversed by the treatment of Nar, a natural flavanone. Our studies identify intracellular Ca as a unique target used by organic solvents in the cytotoxicity and highlight the Ca(2+) ion stabilizer properties of Nar.

Taurine ameliorates 5-flourouracil-induced intestinal mucositis, hepatorenal and reproductive organ damage in Wistar rats: A biochemical and histological study

5-Fluorouracil is one of the most commonly used anticancer drugs for the treatment of various types of cancer but has potential adverse effects such as intestinal mucositis, renal, hepatic, and reproductive organ toxicity. Attention has been given to approaches to reduce the side effects and improve the therapeutic effectiveness of chemotherapeutic drugs. In this study, we have investigated the protective effect of taurine (Tau) on 5-fluorouracil (5-FU) induced adverse effects in Wistar rats. Animals were divided into four groups with six animals (n = 6) in each group. Group I received vehicle only and served as control group. Groups II, III, and IV animals were given oral gavage of 5-FU at 50 mg/kg body weight for 4 days. Tau was given to the animals of groups III and IV 30 min prior to 5-FU administration. We observed marked elevation in the myeloperoxidase (MPO) activity after 5-FU administration, which was reversed by Tau pretreatment. Histological observation of liver, kidney, intestine, testis, and prostate revealed that 5-FU administration resulted in anomalies like distortion of normal cellular architecture, infiltration of inflammatory cells, and loss of cellular integrity. These histopathological changes were markedly suppressed by Tau treatment. In conclusion, biochemical and histological findings of this study suggest that Tau has strong preventive potential against complications of anticancer drug 5-FU and hence Tau may play an important role in combinational chemotherapy to enhance the therapeutic efficacy of anticancer drugs.

18-β Glycyrrhetinic acid alleviates 2-acetylaminofluorene-induced hepatotoxicity in Wistar rats

2-Acetylaminofluorene (2-AAF) is a known hepatic carcinogen which leads to tumour formation in rodents. 18-β Glycyrrhetinic acid (18 β-GA) derived from liquorice plant has various pharmacological properties such as anti-ulcer, anti-inflammatory, antiviral, hepatoprotective and antioxidant. This study is designed to elucidate the chemopreventive properties of 18 β-GA against 2-AAF-induced liver toxicity in Wistar rats and evaluated its effect on inflammatory and tumour promotion marker and activities of different oxidative stress enzymes. Administration of 2-AAF at the dose of (50 mg/kg body weight (b.w.) intraperitoneally (i.p.)) for five consecutive days induces hepatic toxicity, inflammation, oxidative stress and hyperproliferation. Pretreatment with 18 β-GA at two different doses (45 and 75 mg kg−1 b.w.) significantly ameliorates 2-AAF-induced increased lipid peroxidation, alanine transaminase and aspartate transaminase, xanthine oxidase activities and activities of phase-II detoxifying enzymes along with the levels of glutathione content. Administration of 18 β-GA also significantly restored the expressions of proliferating cell nuclear antigen, cyclooxygenase 2, inducible nitric oxide synthase and nuclear factor κB. Furthermore, histological observations also support the preventive effects of 18 β-GA. Our findings suggest that pretreatment with 18 β-GA showed potential hepatoprotective effects via attenuation of oxidative stress, inflammation and hyperproliferation.

Chemopreventive effects of aloin against 1,2-dimethylhydrazine-induced preneoplastic lesions in the colon of Wistar rats

Chemoprevention opens new window in the prevention of all types of cancers including colon cancer. Aloin, an anthracycline in plant pigment, can be utilized as a protective agent in cancer induction. In the present study, we have evaluated the chemopreventive efficacy of aloin against 1,2-dimethylhydrazine (DMH)-induced preneoplastic lesions in the colon of Wistar rats. DMH-induced aberrant crypt foci (ACF) and mucin-depleted foci (MDF) have been used as biomarkers of colon cancer. Efficacy of aloin against the colon toxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, lipid peroxidation, ACF, MDF, histopathological changes, and expression levels of molecular markers of inflammation and tumor promotion. Aloin pretreatment ameliorates the damaging effects induced by DMH through a protective mechanism that involved reduction in increased oxidative stress enzymes (p < 0.001), ACF, MDF, cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6, proliferating cell nuclear antigen protein expression, and tumor necrosis factor-α (p < 0.001) release. From the results, it could be concluded that aloin clearly protects against chemically induced colon toxicity and acts reasonably by inducing antioxidant level, anti-inflammatory and antiproliferative markers.

Perillyl alcohol as a protective modulator against rat hepatocarcinogenesis via amelioration of oxidative damage and cell proliferation

In the present study, we have evaluated the chemopreventive effects of perillyl alcohol (POH) against diethylnitrosamine-initiated and 2-AAF (2-acetylaminofluorine)-promoted hepatocarcinogenesis in Wistar rats. Efficacy of POH against 2-AAF-induced hepatotoxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, histopathological changes and expression levels of proliferative markers. 2-AAF is a potent hepatotoxicant and a hepatic carcinogen that induces its effect by causing oxidative stress. Pre-treatment of POH prevented oxidative stress and tumour incidences. POH suppressed 2-AAF-induced early tumour markers, namely ornithine decarboxylase activity, thymidine phosphorylase and proliferating cell nuclear antigen (PCNA) protein and also suppressed the expression of pro-apoptotic protein P53. Histopathological findings revealed that POH-pretreated groups showed marked recovery. From our results, it could be concluded that POH markedly protects against chemically induced liver cancer and acts possibly by virtue of its antioxidant and antiproliferative activities.

Fixation using cannulated screws and fibular strut grafts for fresh femoral neck fractures with posterior comminution

PURPOSE

To evaluate the use of fibular grafting for fresh femoral neck fractures with posterior comminution.

METHODS

18 women and 15 men aged 20 to 60 years underwent osteosynthesis and fibular strut grafting supplemented with 7.0-mm cannulated hip screws for Garden grades III (n=21) and IV (n=12) femoral neck fractures associated with posterior comminution. All fractures were reduced by closed methods, and no hip was aspirated. Clinical and radiological outcomes were evaluated.

RESULTS

The mean delay in presentation after injury was 3.2 (range, 1-12) days. The mean delay in operation was 8.8 (range, 5-21) days. The mean follow-up period was 2 (range, 1-4) years. According to the Harris hip score, outcome was good to excellent in 20 patients, fair in 7, and poor in 6. 27 of the 33 patients achieved bone union after a mean of 4.7 (range, 4.2-7) months. In 5 patients, the bone was united with a mean of 10º of varus collapse and a mean of 1 cm of shortening. Six patients had non-union. Other complications included screw migration in the joint space (n=1), graft migration into the joint space (n=3), and screw pullout (n=5). No patient had avascular necrosis of the femoral head.

CONCLUSION

Osteosynthesis and fibular grafting for freshly displaced femoral neck fractures with posterior comminution is an inexpensive and technically less demanding procedure for retaining a stable, painless, mobile, and functional hip.

Primary hydatid cyst of pancreas with acute pancreatitis

CONTEXT

Primary hydatid disease of the pancreas is very rare and even rarer to cause pancreatitis.

CASE REPORT

We report the case of a 20-year-old man who presented with abdominal pain and an epigastric mass. A diagnosis of a pancreatic hydatid cyst was established by ultrasonography and CT scan before surgery. The treatment consisted of laparoscopic cyst evacuation with omentoplasty. The recovery was uneventful and the patient has remained symptom free so far.

CONCLUSIONS

Hydatid disease should be considered in the differential diagnosis of all cystic masses in the pancreas, especially in the geographical regions where the disease is endemic.

Neoadjuvant chemo-radiotherapy and rectal cancer: can the UK watch and wait with Brazil?

OBJECTIVE

It has recently been reported that up to one-third of patients with nonmetastatic distal rectal cancer managed with neoadjuvant chemoradiation therapy (CRT) had a complete clinical response (cCR) to treatment. In the selected cases, this has been used as the sole treatment. The aim of this study was to determine the frequency of complete pathological response for patients receiving CRT in one centre in the UK.

METHOD

Patients receiving 6 weeks of neoadjuvant CRT were identified using the two cancer audit databases in two different tertiary hospitals from January 2002 to November 2007. Pathology was reviewed and the histopathological response of the resected specimen to CRT was evaluated using the Mandard classification (1 = complete response, 5 = no response)

RESULTS

One hundred and thirty-two consecutive patients [median age 61 (range 44-86) years, 90 men] with nonmetastatic locally advanced rectal cancer received neoadjuvant chemo radiotherapy between 2002 and 2007 followed by resection of the tumour. Data were available from 129 patients.

CONCLUSION

Only 13 out of 132 (10%) of patients had a complete pathological response. This is one-third of the cCR previously reported. Nonsurgical therapy for rectal cancer using the Habr-Gama treatment algorithm may only be effective in a very small proportion of patients with rectal cancer in the UK and nonoperative treatment would not be recommended.

Ethnic differences and determinants of diabetes and central obesity among South Asians of Pakistan

AIMS

To study the within ethnic subgroup variations in diabetes and central obesity among South Asians.

METHODS

Data from 9442 individuals age > or = 15 years from the National Health Survey of Pakistan (NHSP) (1990-1994) were analysed. Diabetes was defined as non-fasting blood glucose > or = 7.8 mmol/l, or known history of diabetes. Central obesity was measured at the waist circumference. Distinct ethnic subgroups Muhajir, Punjabi, Sindhi, Pashtun, and Baluchi were defined by mother tongue.

RESULTS

The age-standardized prevalence of diabetes varied among ethnic subgroups (P = 0.002), being highest among the Muhajirs (men 5.7%, women 7.9%), then Punjabis (men 4.6%, women 7.2%), Sindhis (men 5.1%, women 4.8%), Pashtuns (men 3.0%, women 3.8%), and lowest among the Baluchis (men 2.9%, women 2.6%). While diabetes was more prevalent in urban vs. rural dwellers [odds ratio (OR) 1.50, 95% confidence interval (CI) 1.24, 1.82], this difference was no longer significant after adjusting for central obesity (OR 1.15, 95% CI 0.95, 1.42). However, the ethnic differences persisted after adjusting for major sociodemographic risk factors (unadjusted OR for Pashtun vs. Punjabi 0.59, 95% CI 0.42, 0.84, adjusted OR 0.54, 95% CI 0.37, 0.78). Ethnic variation was also observed in central obesity, which varied with gender, and did not necessarily track with ethnic differences in diabetes.

CONCLUSIONS

Unmeasured environmental or genetic factors account for ethnic variations in diabetes and central obesity, and deserve further study.

Assembling the biosynthetic puzzle of crucifer metabolites: indole-3-acetaldoxime is incorporated efficiently into phytoalexins but glucobrassicin is not

First biosynthetic studies utilizing tetradeuterated precursors indicate that the indole glucosinolate glucobrassicin is not a precursor of the phytoalexin brassinin, and that indole-3-acetaldoxime is an efficient precursor.

Distinct types of T-cell help for the induction of a humoral immune response to Streptococcus pneumoniae

Studies have indicated that purified soluble polysaccharide antigens can elicit T cell-independent Ig responses in vivo, although these responses can be modulated by T cells in a noncognate manner. Relatively little is known, however, concerning the parameters that regulate polysaccharide-specific, as well as protein-specific, Ig isotype responses to an intact extracellular bacterium. Using the murine in vivo humoral response to intact Streptococcus pneumoniae as a model it can be shown that CD4+ T-cell receptor alphabeta+ T cells deliver help for both polysaccharide- and protein-specific Ig responses. However, these responses differ fundamentally in their mechanism of action.

Health status of the Pakistani population: a health profile and comparison with the United States

OBJECTIVES

The health status of the Pakistani population was compared with that of the US population to provide a better understanding of the health problems in a developing nation and shed light on the dynamics of selected diseases.

METHODS

Results from the National Health Survey of Pakistan (n = 18,315) and the US National Health and Nutrition Examination Survey (n = 31,311) were compared. Standardized and comparable methods were used in both surveys.

RESULTS

Indicators of undernutrition among children were high throughout Pakistan. Among adults, there were urban-rural differences and economic gradients in indicators of undernutrition and risk factors for heart disease and cancer. In comparison with the US population, the Pakistani population has a higher rate of undernutrition, a lower rate of high cholesterol, and an approximately equal rate of high blood pressure.

CONCLUSIONS

There are major inequalities in health within Pakistan and between Pakistan and the United States. Standardized national health examination survey methodology can be used to monitor health status and plan health transition policy in developing countries.

B7 requirements for primary and secondary protein- and polysaccharide-specific Ig isotype responses to Streptococcus pneumoniae

The requirements for B7 costimulation during an in vivo humoral response to an intact extracellular bacteria have not been reported. In this study we immunized mice with Streptococcus pneumoniae (R36A) to determine the B7 requirements for induction of Ig, specific for two determinants on R36A, the phosphorylcholine (PC) determinant of C-polysaccharide and pneumococcal surface protein A (PspA). We show that the primary anti-PspA response, the development of PspA-specific memory, and the induction of the secondary anti-PspA response in primed mice were completely dependent upon B7 costimulation. Of note, costimulation was required only briefly after the secondary immunization compared with after the primary immunization for optimal induction of Ig. Blockade of B7 costimulation at the time of secondary immunization also completely abrogated the established state of memory, but did not induce tolerance. In contrast to the anti-PspA response, the primary anti-PC response involved only a very short period of B7 costimulation. Whereas B7-2 alone was required for induction of the primary anti-PspA and anti-PC responses, a redundant role for B7-1 and B7-2 was noted for the PspA-specific secondary response. CTLA4Ig blocked both the anti-PC and anti-PspA responses equally well over a wide range of bacterial doses. These studies demonstrate a critical, but variable, role for B7-dependent costimulation during an Ig response to an extracellular bacteria.

Phytoalexins from crucifers: synthesis, biosynthesis, and biotransformation

Phytoalexins play a significant role in the defense response of plants. These secondary metabolites, which are synthesized de novo in response to diverse forms of stress, including fungal infection, are part of the plants' chemical and biochemical defense mechanisms. Phytoalexins from crucifers are structurally and biogenetically related, but display significantly different biological activities. Here, we review work reporting the chemical structures, synthesis, biosynthesis and metabolism of cruciferous phytoalexins, as well as their biological activity towards different microorganisms.

Biotransformation of the phytoalexin camalexin by the phytopathogen Rhizoctonia solani

The unusual metabolism of the cruciferous phytoalexin camalexin by virulent and weakly virulent isolates of the root rot fungus Rhizoctonia solani Kuhn is reported. This biotransformation proceeded via 5-hydroxycamalexin, which was further biotransformed into more polar metabolites. Importantly, the metabolites resulting from transformation of camalexin were significantly less toxic to the pathogen than camalexin. Thus, it was concluded that R. solani can detoxify camalexin through oxidation of the indole ring. The chemistry involved in the structure determination of the intermediates of this pathway, their synthesis as well as antifungal activity is described.

Salmonella typhi rpoS mutant is less cytotoxic than the parent strain but survives inside resting THP-1 macrophages

Transcription of the stationary-phase sigma factor RpoS of Salmonella typhi increased in the macrophage. A single rpoS mutant of S. typhi was constructed to analyze the role of RpoS in intracellular multiplication of the bacterium and host cell killing. This mutant was sensitive to starvation, low pH and hydrogen peroxide; however, it could still multiply inside resting macrophages and was less cytotoxic than the wild-type strain. Therefore, S. typhi might produce RpoS-dependent factors which could contribute to host cell death.

Vi-deficient and nonfimbriated mutants of Salmonella typhi agglutinate human blood type antigens and are hyperinvasive

We generated nonfimbriated mutants from both Vi-positive and -negative Salmonella typhi to analyze the role of type 1 fimbriae and Vi-antigen in bacterial invasion. A Vi-defective mutant of S. typhi GIFU 10007-3 was more invasive than the wild-type strain GIFU 10007. The wild-type strain expressing Vi-antigen did not agglutinate both Saccharomyces cerevisiae and human erythrocytes but Vi-defective mutants were able to agglutinate S. cerevisiae and human erythrocytes. Nonfimbriated mutants from Vi-negative GIFU 10007-3 lost the ability to adhere to S. cerevisiae but still could agglutinate human erythrocytes. The Vi-negative mutant increased secreted proteins and became 5-fold more invasive than the wild-type strain. Nonfimbriated Vi mutants became 50-120-fold more invasive than the wild-type GIFU 10007. To determine why nonfimbriated Vi mutants still agglutinate human red blood cells, we searched bacterial proteins that could bind human blood-type antigens. We finally identified a candidate 37 kDa outer membrane protein that recognized fucosyl-galactose, a structure common to blood type A, B and H antigens.

Amplification of rfbE and fliC genes by polymerase chain reaction for identification and detection of Salmonella serovar Enteritidis, Dublin and Gallinarum-Pullorum

Polymerase chain reaction (PCR) primers for O9 antigen (rfbE) and phase 1 flagellin antigen (fliC) were designed for the rapid identification and detection of Salmonella serovar Enteritidis and Dublin. The rfbE primer pairs selectively amplified the rfbE region of group O9 Salmonella serovars. The fliC primer pairs amplified the DNAs of g,m and g,p-type flagellar antigen; Salmonella serovar Enteritidis, Dublin, and Essen. However, DNA from flagellar-negative Salmonella serovar Gallinarum-Pullorum was also amplified. The sensitivity of PCR primer pairs was 10(4) CFU/assay by boiled DNA preparation and 10(2) CFU/assay by proteinase K-treated DNA preparation.

Comparison of ViaB regions of Vi-positive organisms

We cloned the vipR genes from Salmonella paratyphi C, S. dublin, and Citrobacter freundii strains and compared them with the S. typhi sequence to clarify the genetic relationship of the ViaB regions of Vi-positive organisms. ViaB regions were divided into two groups based on their sequences, the Salmonella and C. freundii groups. The vipR coding sequences of the Salmonella group were identical. Southern blot hybridization results using the full-length ViaB region as a probe support these findings.

Survival of Vi-capsulated and Vi-deleted Salmonella typhi strains in cultured macrophage expressing different levels of CD14 antigen

We examined the intracellular survival of Vi-capsulated (lipopolysaccharide; (LPS)-masked) and Vi-deleted (LPS-exposed) Salmonella typhi strains inside macrophage cell lines. Growth of LPS-exposed S. typhi was inhibited in both mouse and human macrophage cell lines. However, the LPS-exposed strain survived in a CD14-deficient mouse macrophage cell lines. Wild-type S. typhi strain, which expressed the Vi antigen and masked LPS, survived in the resting human macrophage cell line. When the Vi-capsulated S. typhi entered the cells, the production of tumor necrosis factor-alpha (TNF-alpha) was suppressed. In contrast, S. typhimurium and LPS-exposed S. typhi stimulated the macrophages to produce a high level of TNF-alpha.

Roxatidine versus ranitidine in the treatment of patients with duodenal ulcer: a randomized, double-masked, multicenter study

The comparative efficacy of roxatidine and ranitidine in the treatment of patients with acute duodenal ulcer was assessed at 4 and 6 weeks in this multicenter study. Ninety-four of 192 patients were given roxatidine in a single nightly dose of 150 mg, and 98 patients were given ranitidine in a single nightly dose of 300 mg. All the patients had endoscopically proven duodenal ulcer. Of the 171 assessable patients, ulcers were healed in 88% of the roxatidine group (73 of 83) and in 84% of the ranitidine group (74 of 88). No serious adverse events were reported in either group. We conclude that roxatidine 150 mg once daily is as effective and safe for the treatment of acute duodenal ulcer as ranitidine 300 mg once daily.

Positive autoregulation of vipR expression in ViaB region-encoded Vi antigen of Salmonella typhi

vipR was the first gene in the ViaB region found to be involved in production of the Vi capsular antigen in Salmonella typhi and to be transcribed in the same direction as nine downstream genes. To investigate its function, we constructed a nonpolar vipR mutant by inserting a cat cartridge into the vipR gene on the chromosome. Inactivation of the gene decreased its transcriptional level and the levels of the downstream genes. When a functional vipR gene on a low-copy-number plasmid was introduced into the vipR mutant, the transcriptional levels of the chromosomal genes were restored. These results indicate that the vipR gene product acts as a transcriptional activator for the downstream genes. Interestingly, the vipR gene also was positively regulated by its own product. DNA-binding studies showed that protein extract that contained the VipR product specifically retarded the mobility of a 451-bp BspHI-XbaI fragment upstream of the vipR gene. In addition, complementation analysis indicated that the vipR gene was cotranscribed with a least two downstream genes, vipA and vipB. These findings suggest that the VipR product may interact with the regulatory region upstream of the vipR gene and induce operonic mRNA synthesis that includes the vipR and downstream genes.

Marginal leakage of Gallium Alloy root-end fillings: an in-vitro assessment

The sealing ability of amalgam and Gallium Alloy Gallium Filling (GF) root-end fillings was evaluated in vitro using a highly uniform collection of sheep incisor roots. Following ultrasonic canal debridement and orthograde obturation with gutta-percha and sealer, root-end cavities were prepared in 100 roots and filled with amalgam (50 teeth) or Gallium Alloy GF (50 teeth), Twenty-five teeth from each group were subjected to immediate dye leakage assessment under vacuum conditions with methylene blue dye (2%), pH 7. Linear dye penetration was measured following longitudinal splitting. The other 25 teeth from each group were incubated in Ringer's solution for 12 weeks before leakage assessment by the same method. Control teeth were included in each component of the study. Mean linear dye penetration was: amalgam--5.17 mm at baseline, 2.33 mm after 12 week's incubation; Gallium Alloy GF--2.21 mm at baseline, 1.41 mm after 12 week's incubation. The apical marginal seal of both materials improved significantly following storage in Ringer's solution (P<0.001). Gallium Alloy GF provided a better apical seal than amalgam, both at baseline and following storage (P<0.001). Subjective evaluation of the general handling characteristics of Gallium Alloy GF revealed that it was a more difficult material to manipulate than amalgam, largely because of its wetting ability and consequent adhesion to dental instruments.

Development of nested PCR based on the ViaB sequence to detect Salmonella typhi

For a rapid diagnosis of typhoid fever, we developed a nested PCR based on the nucleotide sequence encoding the Vi antigen. All Salmonella typhi strains along with a Salmonella paratyphi C strain were PCR positive. This assay was able to detect S. typhi at the single-cell level.

Euphorcinol: A New Pentacyclic Triterpene from Euphorbia tirucalli

Euphorcinol, a new triterpene of the friedelane group, has been isolated from the fresh and un-dried stem bark of EUPHORBIA TIRUCALLI. The structure 1 is assigned to it on the basis of chemical and spectroscopic studies including 2D-NMR.