Algebraic formulas characterizing an alternative to Guyton's graphical analysis relevant for heart failure.

Although Guyton's graphical analysis of cardiac output-venous return has become a ubiquitous tool for explaining how circulatory equilibrium emerges from heart-vascular interactions, this classical model relies on a formula for venous return that contains unphysiological assumptions. Furthermore, Guyton's graphical analysis does not predict pulmonary venous pressure, which is a critical variable for evaluating heart failure patients' risk of pulmonary edema. Therefore, the purpose of the present work was to use a minimal closed-loop mathematical model to develop an alternative to Guyton's analysis. Limitations inherent in Guyton's model were addressed by 1) partitioning the cardiovascular system differently to isolate left ventricular function and lump all blood volumes together, 2) linearizing end-diastolic pressure-volume relationships to obtain algebraic solutions, and 3) treating arterial pressures as constants. This approach yielded three advances. First, variables related to morbidities associated with left ventricular failure were predicted. Second, an algebraic formula predicting left ventricular function was derived in terms of ventricular properties. Third, an algebraic formula predicting flow through the portion of the system isolated from the left ventricle was derived in terms of mechanical properties without neglecting redistribution of blood between systemic and pulmonary circulations. Although complexities were neglected, approximations necessary to obtain algebraic formulas resulted in minimal error, and predicted variables were consistent with reported values.

Assessment of biodegradability of PVC containing cellulose by white rot fungus

Aims: Polyvinyl chloride (PVC) is the most widely used and environmentally damaging plastic. Processing, production and disposal of PVC cause release of toxic chlorine based compounds into environment. The objective of the present study was to assess the biodegradability of cellulose blended PVC by white rot fungi i.e. Phanerochaete chrysosporium. Methodology and results: Biodegradability of the strain for the polymer was tested on plate assay, sturm test, soil burial and shake flask experiments. The biodegradability of the polymer was determined by visual changes, plate assay and carbon dioxide production. Morphological changes in the polymer such as pits, extensive spotting, clear surface erosion, fungal attachment, roughening and deterioration of some parts were observed using scanning electron microscopy. Chemical changes like appearance and shortening of peaks using fourier transform infrared spectroscopy also confirmed the biodegradability of the polymer. Conclusion, significance and impact of study: The present study confirmed that mixing of small amount of cellulose increases the hydrophilicity of the polymer and lead to its microbial degradation and Phanerochaete chrysosporium has great potential for the treatment of solid waste containing plastics.

Measurement issues when assessing quality of life outcomes for different types of hernia mesh repair.

INTRODUCTION: The NHS is required to collect data from patient reported outcome measures (PROMs) for inguinal hernia surgery. We explored the use of one such measure, the Carolinas Comfort Scale(®) (CCS), to compare long-term outcomes for patients who received two different types of mesh. The CCS questionnaire asks about mesh sensation, pain and movement limitations, and combines the answers into a total score. PATIENTS AND METHODS: A total of 684 patients were treated between January 2007 and August 2008 and were followed up in November 2009. RESULTS: Data on 215 patients who met the inclusion criteria were available (96 patients who received Surgipro™ mesh and 119 who received Parietene™ Progrip™ mesh). Recurrence rates were similar in the Surgipro™ group (2/96, 2.1%) and Progrip™ group (3/118, 2.5%) (Fisher's exact test = 1.0). Chronic pain occurred less frequently in the Surgipro™ group (11/95, 11.6%) than in the Progrip™ group (22/118, 18.6%) (p<0.157). Overall, 90% of CCS total scores indicated a good outcome (scores of 10 or less out of 115). A principal component analysis of the CCS found that responses clustered into two subscales: 'mesh sensation' and 'pain+movement limitations'. The Progrip™ group had a slightly higher mesh sensation score (p<0.051) and similar pain+movement limitations scores (p<0.120). CONCLUSIONS: In this study of quality of life outcomes related to different mesh types, the CCS subscales were more sensitive to differences in outcome than the total CCS score for the whole questionnaire. Future research should consider using the CCS subscales rather than the CCS total score.

Antiviral therapy in HCV-infected decompensated cirrhotics.

Decompensated cirrhosis has traditionally been considered a contraindication to interferon and ribavirin therapy. Whereas, the same may be true for advanced cirrhosis, which is only successfully amenable to liver transplantation (LT), there are reports in the literature in which antiviral therapy was given successfully in selected cases of early hepatic decompensation with an aim to attain sustained viral clearance, halt disease progression, and expect potential (though, often, partial) recovery of hepatic metabolic activity. Antiviral therapy may also be instituted to prevent hepatitis C recurrence after LT (it has even caused removal of some patients from the waiting list for LT). Thus, decompensation per se is no more an absolute contraindication to antiviral therapy. Nonetheless, considering that a large proportion of such patients have pre-existing hematological cytopenias, modifications in antiviral dose regimens and close monitoring is required in order to prevent worsening of the same. Although the final sustained virological response rates attained in these patients are relatively low, successful antiviral therapy is potentially lifesaving which explains the need to go for it. In this article, the pros and cons of antiviral therapy in decompensated liver cirrhosis are reviewed with special emphasis on how to avoid antiviral dose reductions/withdrawals secondary to the development of hematologic side effects by using hematopoietic growth factors.

Managing HCV infection in pediatric age group: suggested recommendations.

Hepatitis C virus (HCV) infection in children is different from the adult infection in many ways, like natural course of the disease; duration, therapeutic response and side effects profile of the drug therapy; and prognosis. Special considerations include consideration on what could be the appropriate time to investigate a suspected child, when to institute drug therapy and how to prevent vertical transmission. Although over the past one decade many landmark studies have greatly increased our insight on this subject, yet we are far from developing a consensus statement. In this article, a concise yet comprehensive review of HCV infection in children - diagnosis and treatment - is given, followed by suggested recommendations at the end. It is hoped that these recommendations will help develop local guidelines on this subject.

Considerations in the management of hepatitis C virus-related thrombocytopenia with eltrombopag.

Thrombocytopenia is a common clinical problem in HCV-infected cases. Multiple studies have consistently shown a rise in platelet count following a successful HCV treatment thus proving a cause-effect relationship between the two. Although, many therapeutic strategies have been tried in the past to treat HCV-related thrombocytopenia (e.g. interferon dose reductions, oral steroids, intravenous immunoglobulins, splenectomy etc), the success rates have been variable and not always reproducible. After the cessation of clinical trials of PEG-rHuMGDF due to immunogenecity issues, the introduction of non-immunogenic second-generation thrombopoietin-mimetics (eltrombopag and Romiplostim) has opened up a novel way to treat HCV-related thrombocytopenia. Although the data is still sparse, eltrombopag therapy has shown to successfully achieve the primary endpoint platelet counts of >/=50,000/muL in phase II& III, randomized, double-blind, placebo-controlled trials. Likewise, though it is premature to claim safety of this drug especially in high-risk patient groups, reported side effects in the published literature were of insufficient severity to require discontinuation of the drug. Based on the current and emerging evidence, a review of the pharmacologic basis, pharmacokinetics, therapeutic efficacy, safety profile and future considerations of eltrombopag in the context of HCV-related thrombocytopenia is given in this article. A MEDLINE search was conducted (1990 to August 2009) using the search terms eltrombopag, HCV, thrombocytopenia.

The inter-operator variability in measuring waist circumference and its potential impact on the diagnosis of the metabolic syndrome.

OBJECTIVE: The International Diabetes Federation (IDF) has proposed ethnicity specific cut-off values for waist circumference, as an essential criterion for the diagnosis of the metabolic syndrome (MetS). However, before introducing waist circumference measurement as part of the clinical examination, or an obligatory criterion for MetS, it is important to ensure that the measurement is reliable and reproducible. STUDY DESIGN: The inter- and intra-operator variability in measuring waist circumference was assessed in a preliminary study of 10 health professionals and the inter-operator variability in clinical practice was assessed in a study of 102 patients. Repeated measures analysis of variance (ANOVA) was used to assess the significance of the inter- and intra-operator variability. RESULTS: Intra-operator variability was not found to be significant in the preliminary study (F = 0.15, p = 0.764). However, the inter-operator variability was significant in both studies (preliminary: F = 4.16, p<0.001, clinical practice study: F = 14.06, p<0.001). In clinical practice, this could lead to disagreement among operators regarding the presence of central obesity in 9% of the patients. After giving written instructions on how to measure waist circumference, the coefficient of variation was not significantly altered (p = 0.202) but the inter-operator variability lost significance (F = 2.34, p = 0.11), suggesting a reduction in systematic error. CONCLUSIONS: Measuring waist circumference is subject to significant inter-operator variability and could potentially lead to misclassifying patients as having the MetS, or not. Better training of health professionals on how to measure waist circumference properly is needed in order to ensure that patients are not misclassified and that international comparisons of the prevalence of the MetS are reliable.

Role of hematopoietic growth factors as adjuncts in the treatment of chronic hepatitis C patients.

Drug-induced hematotoxicity is the most common reason for reducing the dose or withdrawing ribavirin (RBV) and interferon (IFN) therapy in chronic hepatitis C, which leads to the elimination of a possible cure for the patient. Traditionally, severe anemia and neutropenia have been considered as absolute contraindications to start antiviral therapy. This has not however, been the case since the advent of adjunct therapy with hematopoietic growth factors (erythropoietin (EPO) and granulocyte-colony stimulating factor (G-CSF)). Some recent landmark studies have used this adjunct therapy to help avoid antiviral dose reductions. Although the addition of this adjunct therapy has been shown to significantly increase the overall cost of the treatment, this extra cost is worth bearing if the infection is cured at the end of the day. Although more studies are needed to refine the true indications of this adjunct therapy, determine the best dose regimen, quantify the average extra cost and determine whether or not the addition of this therapy increases the sustained virological response rates achieved, the initial reports are encouraging. Therefore, although not recommended on a routine basis, some selected patients may be given the benefits of these factors. This article reviews the current literature on this subject and makes a few recommendations to help develop local guidelines.

Instant nano-hydroxyapatite: a continuous and rapid hydrothermal synthesis.

Nano-particle hydroxyapatite (HA) rods, were rapidly synthesised using a three pump continuous hydrothermal process (using a water feed at up to 400 degrees C and at 24 MPa): the product was obtained as a highly crystalline and phase pure material, without the need for an ageing step or subsequent heat treatment.

Outcome of laparoscopic cholecystectomy in acute and chronic cholecystitis.

OBJECTIVE: To evaluate and compare the outcome of laparoscopic cholecystectomy (LC) in acute and chronic cholecystitis in terms of complications, conversion rates, reason of conversion and hospital stay. METHODS: Between April 1999 and March 2004, we retrospectively evaluated all patients admitted for symptomatic gall bladder disease in the Department of General Surgery, Lahore General Hospital, Lahore, Pakistan. All patients who underwent LC for symptomatic cholelithiasis were included. They were classified as group A [having acute cholecystitis (AC)] and group B [with chronic cholecystitis (CC)] based on the operative findings and histological diagnosis. RESULTS: Out of 725 patients who underwent LC, 173 patients were included in group A and 552 patients in group B. Conversion rate was 6% for group A and O.7% for group B (p<0.0001). Two patients (0.3%) in group B, while one patient (0.5%) in group A sustained bile duct injury (p>0.05). Two patients (1.1%) in group A and 4 patients (0.7%) in group B developed sub-hepatic bile collections (p>0.05). The mean hospital stay was 1.2 +/- 1.1 days for group A and 1.7 +/- 2.1 days for group B (p<0.001). CONCLUSION: Laparoscopic cholecystectomy is a safe and effective procedure in almost all patients presenting with symptomatic cholelithiasis.

Oxygen therapy in hospitalized patients: the impact of local guidelines.

OBJECTIVE: To study the influence of local guidelines on the behaviour of nursing and medical staff to optimize the oxygen use in patients admitted to hospital. METHODS: Study was performed in a district teaching hospital. Guidelines produced suggested indications, monitoring, use of arterial blood gases (ABGs) and advice on when to stop oxygen therapy. The guidelines were implemented both verbally and in writing to all the nursing and medical staff before and after an audit studying the oxygen use by patients on medical and surgical wards. RESULTS: Ninety patients were included in pre-intervention audit and 59 in post-intervention study. Oxygen prescription did not change with guidelines 30% (27/90) vs. 32% (19/59). Nurses administered oxygen better 95% (18/19) vs. 70% (19/27) (P = 0.043) and monitored more frequently using oximetry 91% (54/59) vs. 69% (62/90) (P = 0.001) after the guidelines. Patients with airway disease had their ABGs checked more frequently 87% (14/16) vs. 65% (15/23) on admission and after they started oxygen inhalation 68% (11/16) vs. 34% (8/23). CONCLUSION: The guidelines disseminated verbally and in writing had no influence on oxygen prescription but improved the practice of close monitoring of patients with airway disease. Nurses improved their performance of both administration of oxygen according to the prescribed dose and monitoring with oximetry.

Site-specific specimen preparation by focused ion beam milling for transmission electron microscopy of metal matrix composites.

This work describes the application and usefulness of the focused ion beam (FIB) technique for the preparation of transmission electron microscopy (TEM) samples from metal matrix composite materials. Results on an Aldiamond composite, manufactured by the squeeze casting infiltration process, were chosen for demonstration. It is almost impossible to prepare TEM specimens of this material by any other conventional method owing to the presence of highly inhomogeneous phases and reinforcement diamond particles. The present article gives a detailed account of the salient features of the FIB technique and its operation. One of the big advantages is the possibility to prepare site-specific TEM specimens with high spatial resolution. The artifacts occurring during the specimen preparation, for example, Ga-ion implantation, curtain effects, amorphous layers, bending of the lamella, or different milling behaviors of the materials have been discussed. Furthermore, TEM examination of the specimens prepared revealed an ultrafine amorphous layer of graphite formed at the interface between the Al and diamond particles that may affect the interfacial properties of the composite materials. This may not have been feasible without the successful application of the FIB technique for production of good quality site-specific TEM specimens.

Mini cholecystectomy now a day stay surgery: anaesthetic management with multi modal analgesia.

OBJECTIVE: To develop anaesthetic techniques for mini cholecystectomy in a day care set up. METHODS: Fifty patients in ASA grade I and II scheduled for minicholecystectomy were selected. They were given Inj. Ketoralac 30 mg intramuscular 45 minutes prior to surgery. Inj. pethidine 0.5 mg/kg intravenous was given at induction and Inj. bupivacaine 0.5% plain 10 ml was infiltered into the wound at the end of surgery. RESULTS: The mean age was 43.4 +/- 6.1 years with a preponderance of females (41 of 51). Thirty eight belonged to ASA grade I and 12 were in ASA grade II. Mean duration of surgery was 28.8 +/- 5.1 minutes. Size of minicholecystectomy incision was 3.9 +/- 0.4 cms. Two patients required additional opioid peroperatively, while two patients were given opioids post operatively. They were discharged from the PACUI at aldrete score > or = 9 at 61.4 +/- 6.3 minutes while 47 patients were discharged from PACU II at PADSS score 7 > = or 9,172.1 +/- 11.4 minutes after surgery. The incidence of nausea was 6% with confidence interval of 95% range (5.0-23.3). Three patients were admitted. None of our patients required a readmission. CONCLUSION: Miinicholecystectomy as a day care procedure is safe, with good pain relief facilitating mobility and recovery with multimodal pain management strategy.

Malignant transformation in synovial chondromatosis of the knee?

Although it has been reported, malignant transformation of synovial chondromatosis is rare. We report a case of malignant transformation of synovial chondromatosis in a knee to a low-grade chondrosarcoma, which was treated with synovial excision and total knee replacement. We also present a literature review of the subject. The case illustrates that malignant transformation should be suspected in chronic cases with a sudden exacerbation of symptoms and that interpretation of histology in cartilage lesions is difficult. It also demonstrates that even when guided biopsy techniques are used, the sampling error of a needle biopsy in any large lesion is unavoidable.

Characterization of two different peptides from the venom of the scorpion Buthus sindicus.

Two disulfide-rich, low-molecular mass peptides (approximately 3 kDa and approximately 4 kDa) have been isolated from Buthus sindicus venom using ion-exchange and reverse-phase HPLC. Peptide I has 35 residues with 8 half-cystine residues and is clearly related to four-disulfide core proteins of the neurophysin type and to toxins of other scorpion species (55-63% residue identity). Peptide II, present in low yield, has 28 residues with 6 half-cystine residues and a structure largely dissimilar from that of peptide I and other characterized toxins, although probably still a member of the disulfide core peptide type. Consequently, scorpion venom contains, in addition to toxins characterized before, toxin-like compounds with distant relationships.