Mathematical modelling of pressure-driven micropolar biological flow due to metachronal wave propulsion of beating cilia.

In this paper, we present an analytical study of pressure-driven flow of micropolar non-Newtonian physiological fluids through a channel comprising two parallel oscillating walls. The cilia are arranged at equal intervals and protrude normally from both walls of the infinitely long channel. A metachronal wave is generated due to natural beating of cilia and the direction of wave propagation is parallel to the direction of fluid flow. Appropriate expressions are presented for deformation via longitudinal and transverse velocity components induced by the ciliary beating phenomenon with cilia assumed to follow elliptic trajectories. The conservation equations for mass, longitudinal and transverse (linear) momentum and angular momentum are reduced in accordance with the long wavelength and creeping Stokesian flow approximations and then normalized with appropriate transformations. The resulting non-linear moving boundary value problem is solved analytically for constant micro-inertia density, subject to physically realistic boundary conditions. Closed-form expressions are derived for axial velocity, angular velocity, volumetric flow rate and pressure rise. The transport phenomena are shown to be dictated by several non-Newtonian parameters, including micropolar material parameter and Eringen coupling parameter, and also several geometric parameters, viz eccentricity parameter, wave number and cilia length. The influence of these parameters on streamline profiles (with a view to addressing trapping features via bolus formation and evolution), pressure gradient and other characteristics are evaluated graphically. Both axial and angular velocities are observed to be substantially modified with both micropolar rheological parameters and furthermore are significantly altered with increasing volumetric flow rate. Free pumping is also examined. An inverse relationship between pressure rise and flow rate is computed which is similar to that observed in Newtonian fluids. The study is relevant to hemodynamics in narrow capillaries and also bio-inspired micro-fluidic devices.

Distal Common Bile Duct Tuberculosis with Obstructive Jaundice: A Case Report.

Tuberculosis (TB) isolated in Common Bile Duct (CBD) is very rare and its treatment is somewhat controversial. We report a case of distal CBD tuberculosis diagnosed as cholangiocarcinoma. A 40 year old man presented with obstructive jaundice without abdominal pain, fever or weight loss. Ultrasonography and Magnetic Resonance Cholangio-Pancreatography (MRCP) indicated a mass lesion in the Distal CBD, which caused structure of the distal common bile duct. As Cholangiocarcinoma was suspected, he underwent Whipple procedure (pancreaticoduodenectomy). Histological examination of resected specimen revealed typical features of tuberculosis in the distal CBD, pancreatic head and lymph nodes. The rest of the abdominal cavity was unremarkable. Anti-microbial therapy for tuberculosis is started for 12 month course and he is well.

An accidental intra-arterial injection of phenytoin in a 43-year-old woman.

We report an accidental intra-arterial injection of phenytoin in a 43-year-old woman undergoing ventriculoperitoneal shunt for hydrocephalus. To flush the arterial line with heparin, mistakenly phenytoin was injected which caused cutaneous gangrene along the radial side of the forearm and an absence of pulsation in the radial artery. After flushing the artery with normal saline and lidocaine, the patient was transferred to the Intensive Care Unit. There the patient was put on intravenous heparin that resolved the problem leading to complete recovery of the patient. The case is being reported to emphasize the importance of close surveillance in injecting drugs through the arterial line access.

Peristaltic transport of bi-viscosity fluids through a curved tube: A mathematical model for intestinal flow.

The human intestinal tract is a long, curved tube constituting the final section of the digestive system in which nutrients and water are mostly absorbed. Motivated by the dynamics of chyme in the intestine, a mathematical model is developed to simulate the associated transport phenomena via peristaltic transport. Rheology of chyme is modelled using the Nakamura-Sawada bi-viscosity non-Newtonian formulation. The intestinal tract is considered as a curved tube geometric model. Low Reynolds number (creeping hydrodynamics) and long wavelength approximations are taken into consideration. Analytical solutions of the moving boundary value problem are derived for velocity field, pressure gradient and pressure rise. Streamline flow visualization is achieved with Mathematica symbolic software. Peristaltic pumping phenomenon and trapping of the bolus are also examined. The influence of curvature parameter, apparent viscosity coefficient (rheological parameter) and volumetric flow rate on flow characteristics is described. Validation of analytical solutions is achieved with a MAPLE17 numerical quadrature algorithm. The work is relevant to improving understanding of gastric hydrodynamics and provides a benchmark for further computational fluid dynamic simulations.

Population dynamics, distribution, and species diversity of fruit flies on cucurbits in Kashmir Valley, India.

Given the economic importance of cucurbits and the losses incurred by fruit fly infestation, the population dynamics of fruit flies in cucurbit crops and the influence of abiotic parameters, such as temperature, relative humidity, rainfall, and total sunshine hours per day on the fruit fly population were studied. The study was carried out at six locations; in district Srinagar the locations were Batmaloo, Shalimar, and Dal, while in district Budgam the locations were Chadoora, Narkara, and Bugam (Jammu and Kashmir, India). Various cucurbit crops, such as cucumber, bottle gourd, ridge gourd and bitter gourd, were selected for the study. With regard to locations, mean fruit fly population was highest (6.09, 4.55, 3.87, and 3.60 flies/trap/week) at Batamaloo and Chadoora (4.73, 3.93, 2.73, and 2.73 flies/trap/week) on cucumber, bottle gourd, ridge gourd, and bitter gourd, respectively. The population of fruit flies was significantly correlated with the minimum and maximum temperature. The maximum species diversity of fruit flies was 0.511, recorded in Chadoora. Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) was the most predominant species in both Srinagar and Budgam, followed by B. dorsalis (Hendel) and B. tau (Walker), while B. scutellaris (Bezzi) was found only in Chadoora. Results of the present investigation may be utilized in developing a sustainable pest management strategy in the agroecological system.

Chemical characteristics of aerosols and trace gas distribution over North and Central India.

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 µg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 µg m(-3)) and in rural areas (44 ± 22 µg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 µg m(-3) and 4 to 11 µg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.

Poor tolerability of thalidomide in end-stage oesophageal cancer.

Oesophageal cancer cachexia is a significant clinical problem, resulting in excessive morbidity and mortality. In a pilot study, 10 patients with cachexia due to advanced cancer of the oesophagus gained weight, including lean tissue, after 14-day treatment with thalidomide. Here, we present randomised placebo controlled trial data over a 6-week period to test the hypothesis that thalidomide is superior to placebo in terms of weight gain in patients with cachexia caused by oesophageal cancer. Thalidomide, 200 mg daily, or an identical placebo was given to patients with advanced oesophageal cancer. Total body weight and lean body mass were assessed in addition to drug tolerability and performance indices. Thirty-four patients were recruited. Of these, six given thalidomide and 16 given placebo completed the protocol; all withdrawals were due to adverse drug reactions or complications of disease. Thalidomide showed no benefit over placebo in participants who completed the protocol. These data suggest that thalidomide is poorly tolerated in patients with advanced cancer of the oesophagus and may not ameliorate the progression of cachexia. In the absence of hard supportive evidence, off-licence treatment with thalidomide should be used with great caution as an adjunct to nutritional support in patients with advanced cancer.

Optimal dose of pre-incision/post-incision gabapentin for pain relief following lumbar laminectomy: a randomized study.

BACKGROUND: Gabapentin has been introduced as an effective agent for post-operative pain control. This study aimed to test the effects of pre- and post-incision administration of different doses of gabapentin on post-operative morphine requirement and pain following lumbar laminectomy. METHODS: In this randomized clinical trial, 175 patients were allocated into seven groups of 25 patients each to receive placebo or gabapentin 600, 900 or 1200 mg pre- or post-incision. Total patient-controlled intravenous morphine consumption during the first 24 post-operative hours, and the time to the first demand for morphine were recorded. Pain score at rest (visual analogue scale) was recorded every 30 min in the first 4 h and then every 2 h until 24 h post-operatively. Side-effects were observed. RESULTS: In the first 12 h, morphine consumption was less, pain scores were lower and the time to the first demand for analgesia was longer in groups receiving gabapentin 900 or 1200 mg either pre- or post-incision, compared with placebo and gabapentin 600 mg (P<0.001). There was no difference between gabapentin 900 and 1200 mg. Pain score, morphine consumption and time to the first demand for analgesia in equal pre- or post-incision doses of gabapentin were not significantly different. No differences in the side-effects were observed between groups. CONCLUSION: Gabapentin 900 or 1200 mg, administered either pre- or post-incision, was found to be effective in pain management following lumbar laminectomy. Similar doses of gabapentin provide the same post-operative analgesia whether administered pre- or post-incision.

The effects of prostaglandin E1 on interleukin-6, pulmonary function and postoperative recovery in oesophagectomised patients.

The inflammatory reactions and tissue response after oesophagectomy are leading causes of postoperative morbidity and mortality. We evaluated the effects of intraoperative infusion of prostaglandin E1 (PGE1) on interleukin-6 (IL-6) levels, (A-a) DO2, pulmonary function and complications. This randomised double-blind clinical trial study was performed on patients undergoing transthoracic oesophagectomy due to cancer Thirty patients were randomly allocated to two groups: the PGE1 group (infusion of PGE1 20 ng kg(-1) min(-1)) and a placebo group (infusion of normal saline 0.9%). The infusion was started before induction of anaesthesia and continued until the end of the operation. The groups were comparable in basic characteristics and preoperative pulmonary function. Patients in the PGE1 group were discharged significantly earlier from the intensive care unit (72+/-9 vs 83+/-17 hours) and hospital (13+/-4 vs 18+/-8 days) (P=0.04 and 0.03, respectively). The (A-a) DO2 was significantly less in the PGE1 group at 12 and 24 hours after the operation (P=0.001, P=0.003, respectively). Postoperatively, IL-6 levels were significantly higher in the placebo group than in the PGE1 group. There were no differences in the forced expiratory volume in the first second or forced vital capacity. The findings indicate that infusion of PGE1 attenuates the increase in serum levels of IL-6 in patients undergoing esophagectomy and improves the (A-a) DO2. Stays in the intensive care unit and hospital were shorter in the PGE1 group. However, there were no differences in pulmonary complications.

Post-operative pain relief following intrathecal injection of acetylcholine esterase inhibitor during lumbar disc surgery: a prospective double blind randomized study.

BACKGROUND: As spinal cholinergic receptors participate in the control of somatic pain, this effect could be potentiated by intrathecal injection of a cholinesterase inhibitor, neostigmine. OBJECTIVE: This study was designed to evaluate the effectiveness of intrathecal administration of neostigmine on pain relief after single level lumbar disectomy. METHODS: Sixty-six patients with unilateral extruded lumbar disc were randomly allocated into two groups, neostigmine ('N'), and control ('C'); the former received 100 microg of neostigmine methylsulphate, whereas the latter received placebo intrathecally after termination of the surgery. Visual Analogue Scale was employed to measure post-operative pain, which was a primary outcome of the study. Opiate dosage consumed was also recorded as a primary outcome during the first 24 h following surgery. Nausea and vomiting although important were considered as secondary outcomes. RESULTS: Mean Visual Analogue Scale scores post-operatively at 1, 4 and 8 h were 2.24, 1.82 and 1.88 in group 'N' and 5.36, 5.61 and 4.88 in group C. Mean morphine used intravenously in the first 24 h was 0.9 mg in group 'N' and 4.7 mg in group C. All results were found to be significantly different in the two groups. The frequency of nausea and vomiting was not significantly different in the two groups 'C' (24%) and 'N' (18%). CONCLUSION: Injection of 100 microg hyperbaric neostigmine intrathecally was effective for pain relief, and reduced post-operative opiate demand.

Propofol-alfentanil vs propofol-remifentanil for posterior spinal fusion including wake-up test.

BACKGROUND: Wake-up test can be used during posterior spinal fusion (PSF) to ensure that spinal function remains intact. This study aims at assessing the characteristics of the wake-up test during propofol-alfentanil (PA) vs propofol-remifentanil (PR) infusions for PSF surgery. METHODS: Sixty patients with scoliosis and candidates for PSF surgery were randomly allocated in either alfentanil (PA) or remifentanil (PR) group. After an i.v. bolus of alfentanil 30 microg kg(-1) in the PA group or remifentanil 1 microg kg(-1) in the PR group, anaesthesia was induced with thiopental and atracurium. During maintenance, opioid infusion consisted of alfentanil 1 microg kg(-1) min(-1) or remifentanil 0.2 microg kg(-1) min(-1), in the PA group and the PR group, respectively. All patients received propofol 50 microg kg(-1) min(-1). Atracurium was given to maintain the required surgical relaxation. At the surgeon's request, all infusions were discontinued. Patients were asked to move their hands and feet. Time from anaesthetic discontinuation to spontaneous ventilation (T(1)), and from then until movement of the hands and feet (T(2)), and its quality were recorded. RESULTS: The average T(1) and T(2) were significantly shorter in the PR group [3.6 (2.5) and 4.1 (2) min] than the PA group [6.1 (4) and 7.5 (4.5) min]. Quality of wake-up test, however, did not show significant difference between the two groups studied. CONCLUSION: Wake-up test can be conducted faster with remifentanil compared with alfentanil infusion during PSF surgery.

Oesophageal cancer and cachexia: the effect of short-term treatment with thalidomide on weight loss and lean body mass.

BACKGROUND: Cachexia is common in patients with advanced cancer and has a direct impact on well-being and mortality. AIM: To test the hypothesis that thalidomide can promote weight gain and lean body mass in patients with advanced oesophageal cancer. METHODS: In an open-label study, 11 patients with non-obstructing and inoperable oesophageal cancer were established on an isocaloric diet for 2 weeks, followed by 2 weeks on thalidomide, 200 mg daily. The primary end-points were weight change and lean body mass. Secondary end-points were quality of life and changes in resting energy expenditure. RESULTS: Ten patients completed the study protocol. The average caloric intake remained the same throughout the study period in all patients. Nine of 10 patients (95% confidence interval, 0.60, 0.98) lost weight on diet alone. The mean weight gain on thalidomide in the following 2 weeks was 1.29 kg (median, 1.25 kg). A similar trend was shown in the lean body mass. Eight of nine patients (95% confidence interval, 0.57, 0.98) initially lost lean body mass on diet alone (missing data in one patient). The mean gain in lean body mass on thalidomide in the following 2 weeks was 1.75 kg (median, 1.33 kg). CONCLUSIONS: Thalidomide treatment appeared to reverse the loss of weight and lean body mass over the 2-week trial period.

Retrospective case series analysis of patients with inflammatory bowel disease on azathioprine. A district general hospital experience.

OBJECTIVES: The aim of this study was to look at our practice of using azathioprine and to compare our results with those in published trials both from the point of view of response and also the side-effect profile. DESIGN: A retrospective case series analysis was done on patients with inflammatory bowel disease (IBD) who were on azathioprine at Leicester General Hospital. METHODS: 111 patients (47 males, 64 females, mean age 35.3 years) were included from gastroenterology outpatients records between November 1997 and August 1998. Clinical and demographic details were collected. Response in Crohn's disease was determined using the Harvey-Bradshaw index. In case of ulcerative colitis the following parameters were used: stool frequency; rectal bleeding, weight gain, and general well-being. Logistic regression was performed to look at the influence of age, sex and diagnosis in relation to the response/relapse rate. RESULTS: The average duration of treatment with azathioprine was 28.6 months. The starting dose of 1.53 mg/kg was similar to the maintenance dose (1.51 mg/kg). 58 patients had Crohn's disease and 53 patients were diagnosed with ulcerative colitis. 85 patients were steroid-dependent, 9 steroid-resistant, and 17 patients were started on azathioprine on the basis of extensive disease either seen at the time of endoscopy or radiologically. Improvement in clinical features at 3, 6 and 12 months was 69.5, 77 and 84.1%, respectively. 74% patients showed an improvement in relapse rates during the first year on azathioprine compared to 1 year prior to treatment. 68% patients who had shown improvement at 1 year were no longer taking steroids (p = 0.002). Logistic regression did not show any statistically significant influence of age, sex or diagnosis on response. 4.5% patients had leukopenia requiring dose reductions. Severe leukopenia (leukocyte count <2.5 x 10(9)/l) occurred in 3.6% patients. CONCLUSIONS: Response rates in our IBD patients on azathioprine are comparable with those of the published data despite using a relatively smaller dose.

Electronic absorption spectra of benzoquinone and its hydroxy substituents and effect of solvents on their spectra.

The electronic absorption spectra of 1,4-benzoquinone (BQ) and its 2,5-dihydroxy and tetrahydroxy derivatives have been studied in detail. The interpretation of the electronic bands is made on the basis of PPP and CNDO calculations. It is found that the pi --> pi* transitions are well predicted by the PPP method. The predictions of the CNDO method are however superior both in their accuracy as well as ability to predict the n --> pi* transitions. The effect of solvents on the electronic absorption bands have also been investigated in detail. Linear correlations are found between the solvent's dielectric constant and wavelength of the absorption bands. The solvent shifts are explained on the basis of the polarities of the solute and solvent molecules as well as due to hydrogen bonding.

Electronic spectra of 1-methyl and 2-methyl phenanthrenes and their radical cations.

Electronic spectra of phenanthrene (P), 1-methyl phenanthrene (1-MeP), 2-methyl phenanthrene (2-MeP) and their monopositive ions are investigated experimentally as well as theoretically. The ions were produced by photo-oxidation of the hydrocarbons in boric acid matrix. The electronic absorption spectrum of 2-methyl phenanthrene cation (2-MeP+) is entirely new. For the interpretation of the electronic spectra of neutral and ionized MePs, semi-empirical AM1 (Austin Model 1) calculations are carried out for the first time. The bathochromic shifts in the spectral bands of the neutral and ionized MePs are attributed to 'conjugative' effect. The present experiments reveal that the 448 nm band of 1-methyl phenanthrene cation (1-MeP+) and the 486 nm band of 2-MeP+ show close matching with the respective 450 nm and 488 nm 'diffuse interstellar bands'. This suggests the possibility of the existence of such ionic species in the interstellar matter.

Anesthetic and surgical experience in a case of total vertical craniopagus.

BACKGROUND: A case of craniopagus twins is presented. The twins were attached to each other at the parietal vertex with an interaxis angle of 180 degrees and an interface angle of 90 degrees. To assess the bony, vascular, and nervous system interconnections, the twins underwent computerized tomographic scanning and cerebral angiography under inhalational general anesthesia. CASE DESCRIPTION: To provide adequate skin, tissue expanders were implanted under the scalp at 3 and 7 months of age. Separation became necessary at 1 year of age on an emergency basis, because of respiratory complications in the small twin. Profuse bleeding and hypovolemia led to the death of the healthy big twin. While one would expect that at least one of the twins could have been saved, the small twin also succumbed to air emboli and hypotension hours later. Postmortem examination revealed that the brains were joined at both medial and lateral hemispheric surfaces and shared a common circumferential sinus. CONCLUSION: This case was quite different as regards cerebral anatomy compared to those already reported in the literature.

Sildenafil (Viagra) A breakthrough in the management of an old problem or a risky drug.

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