The effect of local-scale physical heterogeneity and nonlinear, rate-limited sorption/desorption on contaminant transport in porous media

Nonideal transport of contaminants in porous media has often been observed in laboratory characterization studies. It has long been recognized that multiple processes associated with both physical and chemical factors can contribute to this nonideal transport behavior. To fully understand system behavior, it is important to determine the relative contributions of these multiple factors when conducting contaminant transport and fate studies. In this study, the relative contribution of physical-heterogeneity-related processes versus those of nonlinear, rate-limited sorption/desorption to the observed nonideal transport of trichloroethene in an undisturbed aquifer core was determined through a series of miscible-displacement experiments. The results of experiments conducted using the undisturbed core, collected from a Superfund site in Tucson, AZ, were compared to those obtained from experiments conducted using the same aquifer material packed homogeneously. The results indicate that both physical and chemical factors, specifically preferential flow and associated rate-limited diffusive mass-transfer and rate-limited sorption/desorption, respectively, contributed to the nonideal behavior observed for trichloroethene transport in the undisturbed core. A successful prediction of trichloroethene transport in the undisturbed core was made employing a mathematical model incorporating multiple sources of nonideal transport, using independently determined model parameters to account for the multiple factors contributing to the nonideal transport behavior. The simulation results indicate that local-scale physical heterogeneity controlled the nonideal transport behavior of trichloroethene in the undisturbed core, and that nonlinear, rate-limited sorption/desorption were of secondary importance.

Effect of inhalation of salbutamol, beclomethasone dipropionate & ipratropium bromide on mucociliary clearance in some patients with chronic stable bronchial asthma

BACKGROUND & OBJECTIVES

Asthma is now regarded as an inflammatory disease and bronchial inflammation may disrupt mucociliary function. Inhaled drugs may act by improving mucociliary function. The aim of the study was to investigate the effect of salbutamol, ipratropium bromide and beclomethasone on mucociliary clearance in patients with chronic stable asthma and to compare the efficacy of these drugs on mucociliary clearance.

METHODS

Ten patients with chronic stable asthma were enrolled in the study, but two patients did not complete the study. Patients with bronchial asthma were chosen on clinical grounds. (99m)Tc phytate radioaerosol generated through a nebulizer, was given to each patient on four days. After each administration the radioactivity over the thorax was constantly measured in sequential frame mode for 120 min. Radioactivity in the thorax was also measured after 24 h. A base-line pulmonary function test with reversibility was obtained. Salbutamol, ipratropium bromide, beclomethasone dipropionate and placebo inhalation were given randomly to each patient on four days.

RESULTS

The mean age of patients (n = 8) was 36 +/- 9.3 yr and mean duration of symptoms was 5 +/- 6.6 yr. There was no visual impression that mucociliary clearance was enhanced with any of the drugs. The time activity curves did not show any visually recognisable change in slope. In only one patient the curve tended to show a steeper slope with ipratropium inhalation. In the rest of the patients the curves showed no difference at all with medication when compared with placebo. All the quantitative indices analyzed by two-way ANOVA at the end of one and two hours were comparable for the three test drugs and placebo. None of the three test drugs demonstrated statistically significant mucociliary clearance effect compared with placebo. However, the temporal difference in airways clearance efficiency (ACE) was significant with beclomethasone and ipratropium bromide.

INTERPRETATION & CONCLUSION

Inhalation of any of the three drugs tested did not produce any immediate improvement in mucociliary clearance as compared to placebo in patients with stable bronchial asthma suggesting the need for further studies using higher doses of drugs for longer duration in a large sample.

Retrospective and prospective study of head and neck cancer

A prospective clinico pathological study of Head and Neck Cancer cases presenting in E.N.T. OPD was done and its observations were compared with retrospective studies done earlier by Gupta et al (1986), It was seen that carcinoma laryngopharynx was the commonest (38.18%) malignancy seen in the present study followed by carcinoma of Larynx (16.36%) and Oesophagus (14.54%). Carcinoma of the nasopharynx was seen in 12.72% cases followed by carcinoma oropharynx (10.91%), Histopathologically; 98.18% cases were of squamous cell carcinomas and out of these only 31.48% were well differentiated carcinoma. There was only 1 case (1.81%) of occult primary. In the retrospective study, the incidence of cancer of Laryngopharynx was 33.33% followed by oropharynx 16.66% and Larynx and Lymphoma (11.11%) each. Occult primary was observed in 3 cases (5.33%) and carcinoma naspoharynx in 4 cases (4.44%). Poor socioeconomic status, bad orodental hygiene, Plummer-vinson syndrome in females were the commonest predisposing factors in addition to smoking, Pan Masala, Zarda and Gutka chewing in the causation of Head and Neck cancer both in prospective and retrospective studies.

Mucoepidermoid carcinoma of the bronchus: is conservative surgery always justified?

A case of mucoepidermoid carcinoma of the bronchus in a 7-year-old boy is reported. The patient underwent right pneumonectomy. Histologically, the tumor was a low-grade muco-epidermoid carcinoma arising from the bronchus with lymph node metastasis in the drainage area. Presence of lymph node metastasis in this low-grade tumor suggests the possibility of early progression of disease in what has until now been considered a very slow growing tumor. Aggressive surgery may be necessary in these situations.

General anaesthesia in a patient with Brugada syndrome

The successful administration of a combined general and epidural anaesthetic to a patient with Brugada syndrome is reported. A review of the literature is presented.

Traumatic injuries to the incisors in children of South Kanara District. A prevalence study

Trauma to the teeth is a commonly encountered problem. Many studies have stated the prevalence of traumatic injuries, range from 4% to 19.5%. In the present study, the prevalence of traumatic injuries to incisors teeth was studied. The unique feature of this study was that it related the associated causes with the severity of fractures (fracture types). In the present study prevalence was found to be 13.8% and this was associated with various factors such as age group involved, sex, place of injury and the overjet of the dentition.

Genetic mapping of 66 new microsatellite (SSR) loci in bread wheat

In hexaploid bread wheat ( Triticum aestivum L. em. Thell), ten members of the IWMMN ( International Wheat Microsatellites Mapping Network) collaborated in extending the microsatellite (SSR = simple sequence repeat) genetic map. Among a much larger number of microsatellite primer pairs developed as a part of the WMC ( Wheat Microsatellite Consortium), 58 out of 176 primer pairs tested were found to be polymorphic between the parents of the ITMI ( International Triticeae Mapping Initiative) mapping population W7984 x Opata 85 (ITMI pop). This population was used earlier for the construction of RFLP ( Restriction Fragment Length Polymorphism) maps in bread wheat (ITMI map). Using the ITMI pop and a framework map (having 266 anchor markers) prepared for this purpose, a total of 66 microsatellite loci were mapped, which were distributed on 20 of the 21 chromosomes (no marker on chromosome 6D). These 66 mapped microsatellite (SSR) loci add to the existing 384 microsatellite loci earlier mapped in bread wheat.

Insulin: a novel factor in carcinogenesis

Cancer is a leading cause of mortality in the United States. Despite much research on specific carcinogens, the cause of many cancers remains unclear. The identification of novel causative agents offers the potential for cancer prevention. Diseases such as obesity and diabetes mellitus, characterized by hyperinsulinemia, are associated with increased risk of endometrial, colorectal, and breast carcinomas. There is increasing evidence that insulin is a growth factor for tumor formation. The mechanisms underlying insulin-mediated neoplasia may include enhanced DNA synthesis with resultant tumor cell growth, inhibition of apoptosis, and altered sex hormone milieu. The reduced insulin levels seen with physical activity, weight loss, and a high fiber diet may account for decreased cancer risk. The role of newer drugs that restore sensitivity to insulin, thereby reducing hyperinsulinemia, is an exciting potential area of cancer prevention. In this review, we discuss the potential role of insulin as a tumor growth factor.

Dynamic optimization of chemical processes using ant colony framework

Ant colony framework is illustrated by considering dynamic optimization of six important bench marking examples. This new computational tool is simple to implement and can tackle problems with state as well as terminal constraints in a straightforward fashion. It requires fewer grid points to reach the global optimum at relatively very low computational effort. The examples with varying degree of complexities, analyzed here, illustrate its potential for solving a large class of process optimization problems in chemical engineering.

Acetoxy-4-methylcoumarins confer differential protection from aflatoxin B(1)-induced micronuclei and apoptosis in lung and bone marrow cells

The ability of various acetoxy derivatives of 4-methylcoumarins to inhibit the genotoxic changes due to aflatoxin B(1) (AFB(1)) is reported here. Several 4-methylcoumarins (test compounds), such as 7,8-diacetoxy-4-methylcoumarin (DAMC), monoacetoxy-4-methylcoumarin (MAC), 5-N-acetyl-6-acetoxy-4-methylcoumarin (NAMC) and 7,8-dihydroxy-4-methylcoumarin (DHMC) were separately administered intraperitoneally (i.p.) to male wistar rats followed by AFB(1) administration i.p. or intratracheally (i.t.) (2-8 mg/kg b.wt.) and another dose of the test compound. The animals were sacrificed 26h after AFB(1) administration. From animals receiving AFB(1) i.p., bone marrow (BM) cells were isolated and stained with Mayer's haematoxylin and eosin. Micronuclei (MN) in BM were scored by light microscopy. From animals receiving AFB(1) i.t., bronchoalveolar lavage (BAL) was obtained, lung cells (LG) were isolated and stained with fluorochrome 6-diamidino-2-phenylindole (DAPI) for the analysis of MN, apoptotic bodies (AP) and cell cycle variations. Rats were separately treated with the vehicle DMSO to serve as the proper control. AFB(1) caused significant dose-dependent induction of MN in BM as well as LG. AP were observed in LG of rats receiving AFB(1) and was found to correlate with MN induction. DAMC injection caused significant decrease in AP due to AFB(1) in LG and MN in both BM and LG. The effectiveness of MAC was approximately half that of DAMC, thereby indicating that number of acetoxy groups on the coumarin molecule determine the efficacy. The fact that NAMC had no effect either on MN or AP indicate that neither acetoxy group at C-6 nor the N-acetyl group at C-5 facilitate the transfer of acetyl group to P-450 required for inhibition of AFB(1)-epoxidation. DHMC, the deacetylated product of DAMC had no normalizing effect on the induction of MN and AP. These findings confirm our earlier hypothesis that DAMC-mediated acetylation of microsomal P-450 (catalysing epoxidation of AFB(1)) through the action of microsomal transacetylase is responsible for the protective action of DAMC. The relative number and position of acetoxy groups on the coumarin nucleus determine the specificity to the transacetylase necessary for the chemopreventive action.

Patient-initiated treatment of uncomplicated recurrent urinary tract infections in young women

BACKGROUND

Recurrent urinary tract infections (UTIs) are a common outpatient problem, resulting in frequent office visits and often requiring the use of prophylactic antimicrobial agents. Patient-initiated treatment of recurrent UTIs may decrease antimicrobial use and improve patient convenience.

OBJECTIVE

To determine the safety and feasibility of patient-initiated treatment of recurrent UTIs.

DESIGN

Uncontrolled, prospective clinical trial.

SETTING

University-based primary health care clinic.

PARTICIPANTS

Women at least 18 years of age with a history of recurrent UTIs and no recent pregnancy, hypertension, diabetes, or renal disease.

INTERVENTION

After self-diagnosing UTI on the basis of symptoms, participating women initiated therapy with ofloxacin or levofloxacin.

MEASUREMENTS

Accuracy of self-diagnosis determined by evidence of a definite (culture-positive) or probable (sterile pyuria and no alternative diagnosis) UTI on pretherapy urinalysis and culture. Women with a self-diagnosis of UTI that was not microbiologically confirmed were evaluated for alternative diagnoses. Post-therapy interviews and urine cultures were used to assess clinical and microbiological cure rates, adverse events, and patient satisfaction.

RESULTS

88 of 172 women self-diagnosed a total of 172 UTIs. Laboratory evaluation showed a uropathogen in 144 cases (84%), sterile pyuria in 19 cases (11%), and no pyuria or bacteriuria in 9 cases (5%). Clinical and microbiological cures occurred in 92% and 96%, respectively, of culture-confirmed episodes. No serious adverse events occurred.

CONCLUSION

Adherent women can accurately self-diagnose and self-treat recurrent UTIs.

Increasing antimicrobial resistance and the management of uncomplicated community-acquired urinary tract infections

Community-acquired urinary tract infections (UTIs) are among the most common bacterial infections in women. Therapy for these infections is usually begun before results of microbiological tests are known. Furthermore, in women with acute uncomplicated cystitis, empirical therapy without a pretherapy urine culture is often used. The rationale for this approach is based on the highly predictable spectrum of etiologic agents causing UTI and their antimicrobial resistance patterns. However, antimicrobial resistance among uropathogens causing community-acquired UTIs, both cystitis and pyelonephritis, is increasing. Most important has been the increasing resistance to trimethoprim-sulfamethoxazole (TMP-SMX), the current drug of choice for treatment of acute uncomplicated cystitis in women. What implications do these trends have for treatment of community-acquired UTIs? Preliminary data suggest that clinical cure rates may be lower among women with uncomplicated cystitis treated with TMP-SMX when the infecting pathogen is resistant to TMP-SMX. Women with pyelonephritis also have less bacterial eradication and lower clinical cure rates when treated with TMP-SMX for an infection that is resistant to the drug. Therefore, in the outpatient setting, identifying risk factors for TMP-SMX resistance and knowing the prevalence of TMP-SMX resistance in the local community are important steps in choosing an appropriate therapeutic agent. When choosing a treatment regimen, physicians should consider such factors as in vitro susceptibility, adverse effects, cost-effectiveness, and selection of resistant strains. Using a management strategy that takes these variables into account is essential for maintaining the safety and efficacy of treatment for acute UTI.

Antimicrobial resistance among uropathogens that cause community-acquired urinary tract infections in women: a nationwide analysis

Current recommendations for empirical therapy for community-acquired urinary tract infection (UTI) in women hinge on knowledge of antimicrobial susceptibility patterns in the geographic region of the practitioner. We conducted a survey of antimicrobial susceptibilities of 103,223 isolates recovered from urine samples that were obtained in 1998 from female outpatients nationally and within 9 geographic regions in the United States. Resistance of Escherichia coli isolates to trimethoprim-sulfamethoxazole varied significantly according to geographic region, ranging from a high of 22% in the western United States to a low of 10% in the Northeast (P<.001). There were no clinically significant age-related differences in the susceptibility of E. coli to any of the study drugs, but the susceptibility to fluoroquinolones of non-E. coli isolates that were recovered from women who were aged >50 years was significantly lower than that of isolates recovered from younger women (P<.001). The in vitro susceptibility of uropathogens in female outpatients varies according to age and geographic region.

An evaluation of the Airway Management Device

We have evaluated the Airway Management Device (AMD) in 105 anaesthetised patients. We were successful in establishing a clear airway on the first attempt on 69 occasions and unable to establish a patent airway at all in 10 patients. Airway obstruction requiring removal of the device occurred during maintenance of anaesthesia in a further two cases and during emergence in three. Loss of the airway during anaesthesia occurred in eight of 95 patients and could be reversed by manipulation of the airway in six cases. Overall, a mean of 0.56 manipulations per patient were required to establish an airway and a further 0.42 per patient were required during maintenance of anaesthesia. In the 95 patients in whom an airway was established, assisted ventilation was satisfactory in 93, with a leak pressure above 20 cmH2O in 65. Intracuff pressure was measured in 12 cases and was above 100 cmH2O in eight. Minor complications occurred in 12 patients. Blood was visible on removal of the device in six cases.

Identification of the transmembrane dimer interface of the bovine papillomavirus E5 protein

We have developed a genetic method to determine the active orientation of dimeric transmembrane protein helices. The bovine papillomavirus E5 protein, a 44-amino acid homodimeric protein that appears to traverse membranes as a left-handed coiled-coil, transforms fibroblasts by binding and activating the platelet-derived growth factor (PDGF) beta receptor. A heterologous dimerization domain was used to force E5 monomers to adopt all seven possible symmetric coiled-coil registries relative to one another within the dimer. Focus formation assays demonstrated that dimerization of the E5 protein is required for transformation and identified a single preferred orientation of the monomers. The essential glutamine residue at position 17 resided in the dimer interface in this active orientation. The active chimera formed complexes with the PDGF beta receptor and induced receptor tyrosine phosphorylation. We also identified E5-like structures that underwent non-productive interactions with the receptor.

Structural analysis of NSAID binding by prostaglandin H2 synthase: time-dependent and time-independent inhibitors elicit identical enzyme conformations

Nonsteroidal antiinflammatory drugs (NSAIDs) block prostanoid biosynthesis by inhibiting prostaglandin H(2) synthase (EC 1.14.99.1). NSAIDs are either rapidly reversible competitive inhibitors or slow tight-binding inhibitors of this enzyme. These different modes of inhibition correlate with clinically important differences in isoform selectivity. Hypotheses have been advanced to explain the different inhibition kinetics, but no structural data have been available to test them. We present here crystal structures of prostaglandin H(2) synthase-1 in complex with the inhibitors ibuprofen, methyl flurbiprofen, flurbiprofen, and alclofenac at resolutions ranging from 2.6 to 2.75 A. These structures allow direct comparison of enzyme complexes with reversible competitive inhibitors (ibuprofen and methyl flurbiprofen) and slow tight-binding inhibitors (alclofenac and flurbiprofen). The four inhibitors bind to the same site and adopt similar conformations. In all four complexes, the enzyme structure is essentially unchanged, exhibiting only minimal differences in the inhibitor binding site. These results argue strongly against hypotheses that explain the difference between slow tight-binding and fast reversible competitive inhibition by invoking global conformational differences or different inhibitor binding sites. Instead, they suggest that the different apparent modes of NSAID binding may result from differences in the speed and efficiency with which inhibitors can perturb the hydrogen bonding network around Arg-120 and Tyr-355.

The influence of health beliefs on the presentation and consultation outcome in patients with chemical sensitivities

OBJECTIVE

This study was carried out to investigate the impact of the physical effects of a chemical exposure, health and chemical beliefs, and chemical sensitivities treatment preferences on the consultation outcome at a tertiary liaison clinic.

METHOD

Eighty-five patients exposed to a range of chemicals were assessed at a joint medical toxicology and psychiatric clinic. Patient's beliefs about chemicals and health, chemical sensitivities and their treatment preferences were assessed using a 23-item questionnaire.

RESULTS

Fifty-seven patients (69%) had suffered from a range of initial or delayed symptoms that were probably a clear physical consequence of the exposure (Group A), whereas 26 patients (31%) had not (Group B). There were no significant differences found between groups A and B in terms of their diagnosis and their beliefs about health, food, chemicals and chemical sensitivities treatment preferences. However, patients in Group A were significantly more likely to report moderate to severe symptoms in comparison to Group B. Consultation outcome too did not differ between the two groups. The only predictors of consultation outcome were the patients' chemical sensitivities treatment preferences. Patients who at the outset thought that their treatment should comprise of complete avoidance to chemicals, regular monitoring and the use of alternative rather than conventional medicine were significantly less likely to achieve a favourable consultation outcome. Patients' chemical sensitivities treatment preferences were related to the more general beliefs on health, food and the harmful nature of chemicals and were not related to the chemical exposure variables.

CONCLUSION

These findings suggest that addressing patients' treatment preferences and the general beliefs on chemicals, food and health may enhance outcome and perhaps ought to be the target for intervention in context of such a liaison clinic.