Biodegradation, sorption, and transport of 2,4-dichlorophenoxyacetic acid in saturated and unsaturated soils

The fate of an organic contaminant in soil depends on many factors, including sorption, biodegradation, and transport. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model compound to illustrate the impact of these interacting factors on the fate of an organic contaminant. Batch and column experiments performed with a sandy loam soil mixture under saturated and unsaturated conditions were used to determine the effects of sorption and biodegradation on the fate and transport of 2,4-D. Sorption of 2,4-D was found to have a slight but significant effect on transport of 2,4-D under saturated conditions (retardation factor, 1.8) and unsaturated conditions (retardation factor, 3.4). Biodegradation of 2,4-D was extensive under both batch and column conditions and was found to have a significant impact on 2,4-D transport in column experiments. In batch experiments, complete mineralization of 2,4-D (100 mg kg-1) occurred over a 4-day period following a 3-day lag phase under both saturated and unsaturated conditions. The biodegradation rate parameters calculated for batch experiments were found to be significantly different from those estimated for column experiments.

Speech-language pathology and dysphagia: a brief historical perspective

In the past decade, speech-language pathologists have taken a leading role in the management of services for patients with oropharyngeal dysphagia. This article presents the historical perspective of this role, the rationale for assuming the responsibility, and suggests directions for continued involvement.

Why diagnose influenza infections in hospitalized pediatric patients?

The advent of rapid diagnostic testing for respiratory syncytial virus facilitated decisions for isolation of infectious hospitalized patients. However, diagnosing other viruses by clinical examination such as influenza may be difficult. If patients with influenza are not diagnosed on hospital admission, nosocomial infections may occur. The purpose of our study was to identify patients with nosocomial influenza infections during one winter season in a large children's hospital, document the morbidity, identify potential index cases as roommate exposures who were not identified as having influenza at the time of admission and determine ways in which these cases could have been prevented. From December, 1989, to March, 1990, 74 patients were found to have positive influenza cultures; 11 (15%) were determined to be nosocomial in origin. Hospitalization was extended for 6 patients. Additional costs for these 11 patients resulting from influenza infection totaled +83,000. Six index cases were identified as potential exposures to 7 (67%) of those who acquired nosocomial infections. In none of these potential index cases had influenza been considered as an admission diagnosis. Rapid tests for influenza are necessary to identify patients with influenza at admission and to identify hospitalized patients with nosocomial infection to decrease the number of diagnostic tests and institute appropriate isolation procedures.

Enhanced octadecane dispersion and biodegradation by a Pseudomonas rhamnolipid surfactant (biosurfactant)

A microbial surfactant (biosurfactant) was investigated for its potential to enhance bioavailability and, hence, the biodegradation of octadecane. The rhamnolipid biosurfactant used in this study was extracted from culture supernatants after growth of Pseudomonas aeruginosa ATCC 9027 in phosphate-limited proteose peptone-glucose-ammonium salts medium. Dispersion of octadecane in aqueous solutions was dramatically enhanced by 300 mg of the rhamnolipid biosurfactant per liter, increasing by a factor of more than 4 orders of magnitude, from 0.009 to > 250 mg/liter. The relative enhancement of octadecane dispersion was much greater at low rhamnolipid concentrations than at high concentrations. Rhamnolipid-enhanced octadecane dispersion was found to be dependent on pH and shaking speed. Biodegradation experiments done with an initial octadecane concentration of 1,500 mg/liter showed that 20% of the octadecane was mineralized in 84 h in the presence of 300 mg of rhamnolipid per liter, compared with only 5% octadecane mineralization when no surfactant was present. These results indicate that rhamnolipids may have potential for facilitating the bioremediation of sites contaminated with hydrocarbons having limited water solubility.

A cost-effectiveness study of the management of intractable urinary incontinence by urinary catheterisation or incontinence pads

STUDY OBJECTIVE

The aim was to compare the costs and effects of management of intractable urinary incontinence by urinary catheterisation or incontinence pads.

DESIGN

This was a prospective, randomised study comparing catheterisation with pads, supplemented by additional data collected from patients with chronic indwelling catheters. Main outcome measures were costs of equipment, nursing time, patient preference, nursing preference, and clinical and bacteriological assessment of urinary infection.

SUBJECTS

78 intractably incontinent elderly female patients were randomly allocated to management by urinary catheter or pads and toileting. Supplementary data on equipment costs and nursing time were collected from 27 patients, of whom 22 were already catheterised at the time of the randomisation and five were catheterised by the nursing staff after the last date for entry into the randomisation.

MAIN RESULTS

Of the 38 patients randomised to catheterisation, 14 refused consent so only 24 were catheterised on day 1 of the study. There was a rapid removal of catheters, especially in the first six weeks of the study and only four of the randomised catheter patients completed the full 26 weeks of the study. However, eight of the pads patients were catheterised between the 7th and 22nd week because of deteriorating general condition and all retained their catheters for the remainder of the study period. Of 35 patients who had experienced catheters and pads, 12 expressed a clear preference for catheters, 12 for pads, and 11 were undecided. Nurses were in favour of the use of pads, mainly because of concerns about urinary infection with catheters. Comparing costs for patients managed with catheters (532 patient weeks) or pads (903 patient weeks), catheter patients required less nursing time (15.4 v 29.0 h per patient per week) but equipment costs were higher (19.20-24.65 pounds v 8.79-11.35 pounds per patient per week), mainly because of the cost of catheter care (12.75 pounds per patient per week). Asymptomatic bacteriuria was prevalent in both groups but 73% of catheterised patients received treatment for clinical signs of infection compared with 40% of pads patients. Only 30% of patients who were treated had any generalised symptoms of infection.

CONCLUSIONS

Use of catheters reduces nursing time but may increase weekly equipment costs depending on the cost of laundry. Despite the high dropout rate among patients randomised to catheters a minority of patients (12/35) expressed a clear preference for catheters and we believe that more patients with intractable incontinence should be given a trial of catheterisation to assess acceptability. Bacteriuria was prevalent in pads or catheter patients but no major episodes of invasive infection were noted in either group.

Patient tolerance of loxaglate and lopamidol in internal mammary artery arteriography

To compare discomfort caused by ioxaglate and iopamidol, 25 patients scheduled for coronary angiography including internal mammary arteriography were studied. Each patient received both agents. Data were available on 22 randomly selected patients who completed the protocol. Two patients were withdrawn because of unsuccessful internal mammary artery cannulation and one because of idiosyncratic reaction to diazepam. After the internal mammary artery injections, the short-form McGill Pain Questionnaire (SF-MPQ) was completed to evaluate the patient response. Ioxaglate caused significantly less discomfort than iopamidol. Word scale (WS) p less than .05; visual analog scale (VAS) p less than .05. We conclude that ioxaglate is much better tolerated than iopamidol in internal mammary arteriography.

Influenza type A and B infections in hospitalized pediatric patients. Who should be immunized?

Medical records of 99 hospitalized pediatric patients whose respiratory viral cultures yielded influenza type A or B during the winter of 1988/1989 were reviewed. We compared the records of patients considered to be at high risk (n = 43) with those of patients considered to be at low risk (n = 56) to determine differences in morbidity and mortality and if vaccination was warranted. Sixty-six percent of high-risk patients had chronic pulmonary disease. Forty-four percent of the high-risk and 11% of the low-risk patients were hospitalized for 14 or more days. Nosocomial influenza infections were identified in 14% of the high-risk and 4% of the low-risk patients. Four of the high-risk patients and only one of the low-risk patients were intubated. Of the three deaths, two occurred in the high-risk group. None of the high-risk patients who experienced significant morbidity had been immunized. We need to immunize high-risk patients, particularly high-risk pulmonary patients.

Reduction (dethiolation) of protein mixed-disulfides; distribution and specificity of dethiolating enzymes and N,N'-bis(2-chlorethyl)-N-nitrosourea inhibition of an NADPH-dependent cardiac dethiolase

The S-thiolated proteins phosphorylase b (Phb) and carbonic anhydrase III (CAIII) were prepared with [3H]glutathione in a reaction initiated with diamide. These substrates were used to measure the rate of reduction (dethiolation) of protein mixed-disulfides by enzymes with properties similar to those of thioredoxin and glutaredoxin. This enzyme activity is termed a dethiolase since the identities of the enzymes are still unknown. The dethiolation of either S-[3H]glutathiolated Phb or S-[3H]glutathiolated CAIII was employed in tissue assays and for study of two partially purified dethiolases from cardiac tissue. NADPH-dependent dethiolase activity was most abundant except in rat liver and muscle. Total dethiolase activity was approximately 10-fold higher in neutrophils, 3T3-L1 cells, and Escherichia coli than in other sources. Rat skeletal muscle had 3- to 4-fold higher dethiolase activity than rat heart or liver. These data indicate that protein dethiolase activity is ubiquitous and that normal expression of the two dethiolase activities varies considerably. A partially purified cardiac NADPH-dependent dethiolase acted on Phb approximately 1.5 times faster than CAIII, and a glutathione (GSH)-dependent dethiolase acted on Phb 3 times faster than CAIII. The Km for glutathione for the GSH-dependent dethiolase was 15 microM with Phb as substrate and 10 microM with CAIII. Thus, the GSH-dependent dethiolase is probably not affected by normal changes in the cardiac glutathione content (normally approximately 3 mM). Partially purified cardiac NADPH-dependent dethiolase was inactivated by BCNU (N,N'-bis(2-chloroethyl)-N-nitrosourea) and the GSH-dependent dethiolase was unaffected under similar conditions. In a soluble extract from bovine heart, 200 microM BCNU inhibited NADPH-dependent dethiolase by more than 60% but did not affect GSH-dependent activity. These results demonstrate that BCNU is a selective inhibitor of the NADPH-dependent dethiolase.

Predicting schizophrenia outcome with self-report measures of family interaction

This study is based on 18 patients admitted to a psychiatric hospital with a DSM-III-R diagnosis of schizophrenia who currently were living with one or both parents. Patients and parents completed several questionnaire, including the Parental Bonding Index (PBI), the Family Environment Scale (FES), the Hostility and Direction of Hostility Questionnaire (HDHQ), and the Brief Symptoms Inventory. Observer ratings of patients' symptoms also were made. Outcome was predicted best by patients' ratings of mothers on the PBI and by mothers' scores on the HDHQ Criticism of Others scale. Other significant outcome predictors were the number of previous admissions to hospital, patients' scores on the HDHQ Projected Hostility scale and the FES Expressiveness scale, and fathers' scores on the FES Achievement-Orientation scale.

Exercise body surface potential mapping in single and multiple coronary artery disease

Body surface ST integral maps were recorded in 36 coronary artery disease (CAD) patients at: rest; peak, angina-limited exercise; and, 1 and 5 min of recovery. They were compared to maps of 15 CAD patients who exercised to fatigue, without angina, and eight normal subjects. Peak exercise heart rates were similar (NS) in all groups. With exercise angina, patients with two and three vessel CAD had significantly (p less than 0.05) greater decrease in the body surface sum of ST integral values than patients with single vessel CAD. CAD patients with exercise fatigue, in the absence of angina, had decreased ST integrals similar (NS) to patients with single vessel CAD who manifested angina and the normal control subjects. There was, however, considerable overlap among individuals; some patients with single vessel CAD had as much exercise ST integral decrease as patients with three vessel CAD. All CAD patients had persistent ST integral decreases at 5 min of recovery and there was a direct correlation of the recovery and peak exercise ST changes. Exercise ST changes correlated, as well, with quantitative CAD angiographic scores, but not with thallium perfusion scores. These data suggest exercise ST integral body surface mapping allows quantitation of myocardium at ischemic risk in patients with CAD, irrespective of the presence or absence of ischemic symptoms during exercise. A major potential application of this technique is selection of CAD therapy guided by quantitative assessment of ischemic myocardial risk.

Phosphorylase and creatine kinase modification by thiol-disulfide exchange and by xanthine oxidase-initiated S-thiolation

The reaction of glycogen phosphorylase b and creatine kinase with glutathione disulfide, cystine, and cystamine was compared by direct analysis on electrofocusing gels. This method was useful for individual proteins or for mixtures of the proteins. Millimolar concentrations of glutathione disulfide were required for both proteins and the rate of modification of each protein was similar. The reaction of glutathione disulfide with creatine kinase was inhibited by reduced glutathione (GSH), but the effect on the reaction with phosphorylase was minimal. Cystine and cystamine were required in micromolar amounts to effectively form the disulfide adducts. Both proteins were modified by cystine but cystamine reacted only with phosphorylase. Cystamine (10 microM) was an effective inhibitor of the reaction of phosphorylase b with 2 mM glutathione disulfide. S-thiolation of creatine kinase inactivated the enzyme and a direct assay of the enzyme activity could be used to quantitate S-thiolation of this protein by each of the disulfides. The effect of each disulfide on enzyme activity confirmed the results obtained by gel electrofocusing. Glutathione disulfide and cystine both inactivated the enzyme while cystamine had no effect on the activity. S-thiolation of phosphorylase had no observable effect on any activity parameter, but it effectively prevented binding of phosphorylase to high-molecular-weight glycogen, probably at the glycogen storage site of phosphorylase. The rate of S-thiolation of a mixture of phosphorylase and creatine kinase by thiol-disulfide exchange with glutathione disulfide was compared to the rate of S-thiolation of these proteins by a xanthine oxidase-initiated process (presumably due to protein sulfhydryl activation by reactive oxygen species). The xanthine oxidase-initiated mechanism was somewhat faster than thiol-disulfide exchange with both proteins. It was shown that GSH inhibited S-thiolation of creatine kinase by this mechanism as well as by thiol-disulfide exchange. It is suggested that both mechanisms may play a role in protein S-thiolation in vivo. For proteins that are typified by creatine kinase, the concentration of GSH in the cells may determine whether the S-thiolated form of the protein accumulates. For proteins typified by phosphorylase b, the accumulation of S-thiolated forms may be more independent of GSH.

Persistent changes in the body surface electrocardiogram following successful coronary angioplasty

One hundred twenty-lead body surface potential maps (BSPMs) were recorded immediately before and 24 hours after coronary angioplasty (PTCA) in 24 patients with symptomatic coronary artery disease (single-vessel in 21 and two-vessel in 3). All PTCAs were uncomplicated and successful. The modified Gensini score decreased in every patient and the mean score fell from 43 +/- 36 to 21 +/- 28 (p less than 0.001). Resting spatial patterns of QRS, ST-segment, and T wave integral distributions over the torso surface were unchanged from before to after PTCA. Quantitative temporal subtraction maps, however, revealed a large precordial area of decreased T wave integral values after PTCA. The sum (sigma) positive T wave integrals fell from 20,501 +/- 10,544 microV.s before PTCA to 17,647 +/- 10,310 microV.s after PTCA (p less than 0.02). In contrast, the sigma positive QRS (10,115 +/- 4,848 microV.s before PTCA vs. 9,656 +/- 4,556 microV.s after PTCA) and the sigma negative ST integrals (-2,489 +/- 1,467 microV.s before PTCA vs. -2,359 +/- 1,505 microV.s after PTCA) were unchanged (NS). Thus, successful PTCA does not produce any persistent change in depolarization or early repolarization electrocardiographic variables but is associated with a decrease in late repolarization potentials that persists for at least 24 hours after the procedure. The pathophysiology of this persistent change is speculative, but myocardial ischemia during the PTCA procedure is a likely possibility. The clinical significance, including predictive value for subsequent stenosis, and the natural history of T wave effect remain incompletely defined. These data suggest that measures to decrease myocardial ischemia during PTCA are warranted.

Using phonation time to estimate vital capacity in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease in which progressive respiratory weakness is usually the proximate cause of death. Since continued assessment of respiratory function is important in predicting progression, phonation time was measured in a group of 41 ALS patients and correlated with measured vital capacity. The findings show that the variance in phonation time accounts for nearly 50% of the variability of vital capacity, and therefore, successive measurements of phonation time are a useful means of estimating the loss of vital capacity.

Evidence from Liposome Encapsulation for Transport-Limited Microbial Metabolism of Solid Alkanes

The recalcitrance of xenobiotics may be caused by an absence of transforming enzymes or by their inability to enter microbial cells. A nondestructive method for differentiating between these two possibilities is described. The solid n -alkanes octadecane (C 18 ) and hexatriacontane (C 36 ) were encapsulated into phosphatidylcholine bilayers (liposomes). The uptake and metabolism rates of encapsulated and unencapsulated substrates were then compared. During 1 h at 25°C, a Pseudomonas isolate took up 1.3% of radiolabeled and unencapsulated C 18 (solid state) versus 23.5% of labeled and encapsulated C 18 . Growth at 25°C occurred with an apparent k s of 2453 ± 148 mg/liter. Liposome encapsulation decreased this K s to 60 ± 12 mg/liter. At 34°C, growth on C 18 (liquid state) occurred with an apparent K s of 819 ± 83 mg/liter and on the readily available carbon source succinate, K s values were 80 ± 10 and 13 ± 7 mg/liter at 25 and 34°C, respectively. At 25°C, the isolate grew on C 36 with an apparent K s of 2,698 ± 831 mg/liter. Liposome encapsulation decreased the K s more than 60-fold to 41 ± 7 mg/liter, resulting in the complete utilization of 400 mg of C 36 per liter in 16 h. Since controls excluded the metabolic utilization of phosphatidylcholine, the results clearly identify transport limitation as the cause for C 36 recalcitrance.

Amyotrophic lateral sclerosis severity scale

The amyotrophic lateral sclerosis (ALS) severity scale has been developed to provide an ordinal staging system and a means of rapid functional assessment for patients with ALS. The scale allows an examiner to evaluate the symptoms of ALS numerically in four categories that describe speech, swallowing, lower extremity, and upper extremity abilities. These scores, combined with a vital capacity measured on a hand-held respirometer, provide a rapid, accurate assessment of a patient's disease status and can be used for treatment planning. The ALS severity scale has been shown to have an average estimated reliability coefficient of 0.95 between examiners. Speech ratings were correlated greater than 0.80 for objective speech measures. Rates of progression of the total score in a small group of patients ranged from -3.4 to -24.0 points/year with a mean of -11.3 points/year.

Photolysis primes biodegradation of benzo[a]pyrene

14C-labeled benzo[a]pyrene (BaP) was used as a model-compound for polycyclic aromatic hydrocarbons (PAH) in order to assess the effect of photolytic pretreatment on the subsequent fate of BaP in sewage sludge and soil test systems. Photolysis was performed in methanolic solution with or without 0.1 M H2O2, under either UV light (300 nm) or natural sunlight. The presence of H2O2 greatly enhanced the rate of photolysis both with UV and with natural sunlight. Intact BaP resisted biodegradation in both test systems. Photolysis transformed BaP to polar materials that were subject to increased mineralization and binding in both biological test systems. As shown by the Ames assay, photolysis decreased the mutagenicity of BaP to test strains TA98 and TA104 only moderately. The photolysate had an increased acute toxicity and lost its need for activation by S-9 enzymes. However, during subsequent incubation in soil or sewage sludge, mutagenicity decreased rapidly by one to two orders of magnitude and acute toxicity disappeared due to the mineralization and binding of photoproducts to humic materials. Photolysis of BaP and similar PAH compounds represents a useful treatment option that could be applied to certain PAH-containing petroleum refinery sludge and to coal tar residues in order to facilitate their detoxification and environmentally safe disposal.

Body surface potential maps with low-level exercise in isolated left anterior descending coronary artery disease

One hundred and twenty-lead body surface potential maps (BSPMs) were recorded at rest, at immediate cessation of exercise and after 1 (early) and 5 minutes (late) of recovery in 14 patients with isolated, critical, left anterior descending (LAD) coronary artery stenosis. Exercise endpoints, at an average peak rate of 98 +/- 13, were usual pain worsening in 13 LAD patients, and diagnostic ST depression in lead V5 in 1 patient. Twelve patients also had positive thallium scans. BSPMs were also recorded in 8 normal subjects who exercised to peak heart rates similar to those of the LAD subjects. Spatially, there were similar exercise changes in QRS and ST-segment integral patterns over the precordium and inferior torso in both groups. These were transient in the control group but persisted to late recovery in the LAD group, particularly for ST integral. Quantitatively, multivariate analysis revealed significant temporal differences between the 2 groups. However, the only independent BSPM variable was the sum of ST integral decrease, averaging --2,323 +/- 1,809 microV.s for normal patients between rest and immediate cessation of exercise, compared with -3,828 +/- 2,329 microV.s for the LAD patients (p less than 0.05). Late recovery minus rest difference averaged -1,264 +/- 1,080 microV.s for normal subjects and -2,575 +/- 1,844 microV.s for LAD patients (p less than 0.01). To control for the physiologic changes of exercise, the ST integral temporal differential maps of the normal subjects were subtracted from those of the LAD patients and the sum of negative intergroup differences was assumed to reflect only ischemia. Correlation of ST integral ischemia values at immediate cessation of exercise and late recovery was high (r = 0.88); however, intertechnique correlations of the BSPM variables with quantitative angiographic scores and thallium perfusion scan scores revealed generally low r values (range 0 to 0.52). These data demonstrate that ischemic repolarization changes are detectable and quantifiable by BSPM at low levels of cardiac stress in patients with 1-vessel disease when the usual electrocardiographic criteria of myocardial ischemia are frequently absent. The data further suggest that ST integral changes reflective of myocardial ischemia persist well after the exercise recovery period and that they are complementary to, rather than substitutionary for, other indirect measures of myocardial ischemia.

The development of a new service for older adults

In July, 1986, Wesley Long Community Hospital, Greensboro, North Carolina, opened its Older Adult Unit. Staffed to accommodate twelve patients, the unit is often operating at capacity. Key to the success of the unit is the process the hospital followed in its development. The hospital tested its preliminary concept for the unit with its consumer populations and tailored the concept to address the needs specifically identified by the populations. In addition, the hospital recognized the importance of an educational role in the promotion of a new service and incorporated this in its marketing strategy. This article outlines the steps followed in the development and successful introduction of the unit.

Management of bulbar symptoms in amyotrophic lateral sclerosis

The bulbar symptoms of ALS include difficulty with the management of swallowing, saliva, aspiration, and communication. These symptoms originate from the disability of the oropharyngeal muscles and actually represent varying degrees of severity of a single problem. The management of these symptoms requires the concerted effort of a rehabilitation team, which should include a surgeon, speech pathologist, neurologist, psychosocial worker, and dietitian. Early education of the patient and patient's family greatly facilitates successful management of bulbar symptoms. Early recognition of the signs of dysphagia, aspiration, and communicative disability are important in order to provide solutions before severe and possibly life-threatening debilitation occurs. The treatments and techniques presented in this chapter must be applied to each patient on an individual basis. The moral and social decisions regarding the providing or withholding of treatment to ALS patients are difficult ones. It is important, however, to realize that management decisions of ALS patients must deal not only with the quantity of life but also the quality of life. This distinction often falls into a 'gray zone' with management of bulbar symptoms since swallowing difficulties are life-threatening as well as uncomfortable. One of the difficulties that we present ourselves as health care providers in ALS is that, more often than not, our patient is in a noncommunicative position and cannot contribute to treatment decisions. If careful and aggressive care is taken to preserve the communicative abilities of our patients, the difficult situation of making decisions based on the family's inclinations and our own inclinations can be avoided. When we are confronted with a decision to maintain or cease support for a patient, the moral and emotional issues that present can be overwhelming. However, the patient's input, if it were direct and included the ability to express complex thoughts, could often provide the information necessary to make the decisions more clear.