The effect of boiling water on disinfection by-product exposure

Chloraminated and chlorinated waters containing bromide were used to determine the impact of boiling on disinfection by-product (DBP) concentrations. No significant changes were detected in the concentrations of the dihalogenated haloacetic acids (DXAAs) (i.e., dichloro-, bromochloro-, dibromoacetic acid) upon boiling of chloraminated water, whereas the levels of the trihalogenated haloacetic acids (TXAAs) (i.e., trichloro- (TCAA), bromodichloro- (BDCAA), dibromochloroacetic acid (DBCAA)) decreased over time (e.g., 9-37% for TCAA). Increased DXAA concentrations (58-68%) were detected in the boiled chlorinated sample, which likely resulted from residual chlorine reacting with DXAA precursors. TCAA concentration was unchanged after boiling chlorinated water for 1 min, but a 30% reduction was observed after 5 min of boiling. BDCAA concentrations decreased 57% upon boiling for 1 min and were completely removed after 2 min of boiling, whereas DBCAA was removed after boiling chlorinated water for 1 min. Trihalomethane concentrations were reduced in both chloraminated (74-98%) and chlorinated (64-98%) water upon boiling. Boiling chloraminated water for 1 min reduced chloroform concentration by 75%. Chloroform was reduced by only 34% in chlorinated water after a 1 min boil, which indicates that simultaneous formation and volatilization of chloroform was occurring. Most of the remaining DBPs (e.g. haloketones, chloral hydrate, haloacetonitriles) were removed by at least 90% after 1 min of boiling in both samples. These data suggest that other mechanisms (e.g., hydrolysis) may have been responsible for removal of the non-volatile DBPs and further highlight the importance of examining individual species when estimating thermal effects on DBP concentrations.

Environmental determinants of Parkinson's disease

Increasing toxicologic and epidemiologic evidence suggests that pesticides and other environmental exposures are associated with idiopathic Parkinson's disease. Using a case-control study, the authors examined the impact of farming, pesticide use, rural residence, and well water use (including critical periods of childhood exposure) on the risk of Parkinson's disease. After adjustment for confounding, > or = 40 years of well-water exposure (compared to no well water use) was associated with an increased risk of Parkinson's disease (OR = 7.1; 95% CI: 2.3-22.1). The authors found an increased risk of Parkinson's disease (OR = 2.1; 95% Cl: 0.7-6.4) for well water use during the first 20 years of life (compared with <20 years of exposure) and saw some suggestion of an exposure-response relationship with increasing childhood exposure. Farming and pesticide use (occupational or residential) was not associated with Parkinson's disease but exposure assessment limitations warrant further investigation.

The effect of disinfection by-products and mutagenic activity on birth weight and gestational duration

Epidemiologic studies of disinfection by-products have traditionally focused on total trihalomethane (TTHM) concentration as a surrogate for maternal exposure during pregnancy. We used birth certificate data on 196,000 infants to examine the effect of third-trimester exposures on various indices of fetal development. We examined the effect of town-average concentrations of TTHM and additional exposure metrics in relation to mean birth weight, mean gestational age, small for gestational age (SGA) infancy, and preterm delivery. Trihalomethane data (TTHM, chloroform, and bromodichloromethane) from 1995-1998 were available for 109 towns in Massachusetts. Data from 1997-1998 on haloacetic acid (total haloacetic acids, dichloroacetic acid, and trichloroacetic acid), 3-chloro-4-(dichloromethyl)-5- hydroxy-2(5H)-furanone (MX), and mutagenicity were available for a limited number of towns. We observed reductions in mean birth weight (12-18 g) for maternal trihalomethane exposures > the 90th percentile compared with those < the 50th percentile. Birth weight reductions were detected for chloroform exposures > 20 microg/L and TTHM exposures > 40 microg/L. Elevated trihalomethanes were associated with increases in gestational duration and a reduced risk of preterm delivery. We found evidence of an exposure-response effect of trihalomethanes on risk of SGA, with odds ratios (ORs) ranging from 1.09 to 1.23 for bromodichloromethane exposures > 5 microg/L. Elevated mutagenic activity was associated with SGA [OR = 1.25; 95% confidence interval (CI), 1.04 to 1.51] and mean birth weight (-27 g; 95% CI, -54 to -1). Although smaller in magnitude, our findings are consistent with previous studies reporting associations between trihalomethanes and SGA. These data also suggest a relationship between fetal development indices and mutagenic activity independent of exposure to trihalomethanes, haloacetic acids, and MX.

Dynamics of 5S rDNA in the tilapia (Oreochromis niloticus) genome: repeat units, inverted sequences, pseudogenes and chromosome loci

In higher eukaryotes, the 5S ribosomal DNA (5S rDNA) is organized in tandem arrays with repeat units composed of a coding region and a non-transcribed spacer sequence (NTS). These tandem arrays can be found on either one or more chromosome pairs. 5S rDNA copies from the tilapia fish, Oreochromis niloticus, were cloned and the nucleotide sequences of the coding region and of the non-transcribed spacer were determined. Moreover, the genomic organization of the 5S rDNA tandem repeats was investigated by fluorescence IN SITU hybridization (FISH) and Southern blot hybridization. Two 5S rDNA classes, one consisting of 1.4-kb repeats and another one with 0.5-kb repeats were identified and designated 5S rDNA type I and type II, respectively. An inverted 5S rRNA gene and a 5S rRNA putative pseudogene were also identified inside the tandem repeats of 5S rDNA type I. FISH permitted the visualization of the 5S rRNA genes at three chromosome loci, one of them consisting of arrays of the 5S rDNA type I, and the two others corresponding to arrays of the 5S rDNA type II. The two classes of the 5S rDNA, the presence of pseudogenes, and the inverted genes observed in the O. niloticus genome might be a consequence of the intense dynamics of the evolution of these tandem repeat elements.

Effect of trihalomethane exposure on fetal development

AIMS

To examine the effect of trimester specific and pregnancy average total trihalomethane (TTHM) exposure on infant birth weight, low birth weight, and intrauterine growth retardation in term births, as well as gestational age and preterm delivery in all births.

METHODS

Cross sectional analysis of 56 513 singleton infants born to residents of Massachusetts during 1990. City specific aggregate data were used to estimate maternal exposure to TTHM concentration; individual maternal information was used to adjust for confounding.

RESULTS

Increased pregnancy average and second trimester TTHM exposure were associated with small for gestational age and reductions in birth weight after adjusting for potential confounding variables. Compared to </=60 micro g/l, pregnancy average TTHM exposure over 80 micro g/l was associated with a 32 g reduction in birth weight. There was a 23 g reduction in birth weight in infants born to mothers exposed to greater than 80 micro g/l TTHM during the second trimester. For each 20 micro g/l increase in TTHM, the estimated reduction in birth was 2.8 g for pregnancy average exposure and 2.6 g for second trimester exposure. An increased risk of small for gestational age births was found for pregnancy average (odds ratio (OR) 1.14; 95% CI 1.02 to 1.26) and second trimester (OR 1.13, 95% CI 1.03 to 1.24) TTHM levels greater than 80 micro g/l. There was no evidence of an association between preterm delivery and increased TTHM levels, but there were slight increases in gestational duration associated with TTHM concentrations.

CONCLUSIONS

Maternal exposure to THMs may be associated with fetal growth retardation. Our findings are consistent with most previous work, although we generally found smaller effects of TTHMs on low birth weight and intrauterine growth retardation.

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and mutagenic activity in Massachusetts drinking water

There is limited information on the prevalence of the potent mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) in U.S. water supplies. We measured MX concentrations and mutagenic activity in tap water samples from 36 surface water systems throughout Massachusetts. We found MX levels much higher (up to 80 ng/L) than previously reported in the United States. We also evaluated the role of water treatment on mutagenic activity and disinfection by-product formation. After adjusting for other covariates, chloramination and filtration were the most important treatment options for reducing mutagenic activity and disinfection by-product formation. Multiple chlorine application (before and after filtration) was associated with increased mutagenicity. Chlorine dose, pH, and total organic carbon were also associated with mutagenicity, MX, and total trihalomethane (TTHM) concentration. Seasonal variation was evident for MX and mutagenic activity, with higher levels occurring in the spring compared to the fall. In contrast, TTHM concentrations were greater in the fall.

Observations on patellar height following opening wedge proximal tibial osteotomy

Patellar height and patellar ligament length were assessed pre- and postoperatively in 28 patients who underwent a medial opening wedge proximal tibial osteotomy for varus gonarthrosis. This procedure produced no significant change in patellar ligament length. Pre- and postoperative Insall-Salvati ratios were 0.96+/-0.12 and 0.97+/-0.15, respectively (P=.30). The Insall-Salvati ratio decreased in 29% of patients, and no patient experienced a decline >0.07. The distance between the patella and tibiofemoral joint line ("patellar height") decreased in 100% of patients. The mean Blackburne-Peel ratio declined from 0.75+/-0.13 to 0.53+/-0.15 (P<.001). Sixty-four percent of the postoperative Blackburne-Peel values satisfied the radiographic criterion for patella infera (Blackburne-Peel ratio <0.54). Whereas the loss of patellar height, historically associated with lateral closing wedge proximal tibial osteotomy, is a function of patellar ligament contracture, the decreased distance between the patella and the tibiofemoral joint line following medial opening wedge proximal tibial osteotomy is a function of joint line elevation. The high incidence of patella infera following medial opening wedge proximal tibial osteotomy may have deleterious effects on patellofemoral biomechanics or may complicate subsequent total knee arthroplasty.

Biologically active sequence (KDI) mediates the neurite outgrowth function of the gamma-1 chain of laminin-1

A neurite outgrowth domain of the gamma1-chain of laminin-1 (RDIAEIIKDI) promotes axon guidance of rat hippocampal neurons, regulates the nuclear movement phase of neuronal migration, and binds to the cellular prion protein (Liesi et al. [1995] J. Neurosci. Res. 134:447-486; Matsuzawa et al. [1998] J. Neurosci. Res. 53:114-124; Graner et al. [2000] Brain Res. Mol. Brain Res. 76:85-92). Using electrophysiology and neuronal culture experiments, we show that this 10 amino acid peptide or its smaller domains induces potassium currents in primary central neurons. Both these currents and the neurotoxicity of high concentrations of the 10 amino acid peptide antigen are prevented by pertussis toxin. The smallest peptide domain capable of inducing both potassium currents and promoting neurite outgrowth of human spinal cord neurons is a tri-peptide KDI. Our results indicate that KDI may be the biologically active domain of the gamma1 laminin, capable of modulating electrical activity and survival of central neurons via a G-protein coupled mechanism. These results expand the wide variety of functions already reported for the members of the laminin-gene family. They suggest that biologically active peptide domains of the gamma1 laminin may provide tools to promote neuronal regeneration after injuries and to enhance neuronal survival during aging and neuronal degeneration.

Molecular organization of 5S rDNA in fishes of the genus Brycon

There are few reports on the genomic organization of 5S rDNA in fish species. To characterize the 5S rDNA nucleotide sequence and chromosomal localization in the Neotropical fishes of the genus Brycon, 5S rDNA copies from seven species were generated by PCR. The nucleotide sequences of the coding region (5S rRNA gene) and the nontranscribed spacer (NTS) were determined, revealing that the 5S rRNA genes were highly conserved, while the NTSs were widely variable among the species analyzed. Moreover, two classes of NTS were detected in each species, characterized by base substitutions and insertions-deletions. Using fluorescence in situ hybridization (FISH), two 5S rDNA chromosome loci that could be related to the two 5S rDNA NTS classes were observed in at least one of the species studied. 5S rDNA sequencing and chromosomal localization permitted the characterization of Brycon spp. and suggest a higher similarity among some of them. The data obtained indicate that the 5S rDNA can be an useful genetic marker for species identification and evolutionary studies.

Arthroscopic visualization of the subscapularis tendon

PURPOSE

This study was conducted to define what portion of the subscapularis tendon is visualized during standard diagnostic glenohumeral arthroscopy and to determine the distance between the inferior aspect of the visible portion of the subscapularis tendon and the axillary nerve.

TYPE OF STUDY

Anatomic (cadaveric) analysis.

METHODS

Six fresh-frozen human cadaveric shoulders were placed in a simulated lateral decubitus position with longitudinal traction and 45 degrees of shoulder abduction. Glenohumeral arthroscopy was performed on each specimen using a standard posterior portal for visualization. The 4 corners of the visible portion of the subscapularis were tagged with arthroscopic sutures. The shoulders were subsequently dissected. The surface area defined by the 4 suture tags and the surface area of the entire subscapularis tendon were calculated for each specimen. The dimensions of these areas and the distance between the inferior aspect of the visible portion of the subscapularis tendon and the axillary nerve were measured with calipers.

RESULTS

The arthroscopically tagged portion of the subscapularis tendon represented only a small percentage (26% +/- 11%) of the entire tendon. The majority of the subscapularis tendon is veiled by the middle and inferior glenohumeral ligaments. There was a significant distance between the inferior aspect of the visible portion of the subscapularis tendon and the axillary nerve (32.8 +/- 6.0 mm). The mean height of the visible portion of the tendon represented 44% of the mean overall height of the subscapularis.

CONCLUSIONS

These data suggest that arthroscopic visualization of the subscapularis is incomplete. Lesions involving the concealed portion of the subscapularis tendon may not be detected arthroscopically. The wide margin of safety between the inferior aspect of the visible portion of the subscapularis tendon and the axillary nerve is relevant to the placement of anteroinferior (trans-subscapularis) arthroscopy portals as well as to performing arthroscopic anterior capsular releases.

Reproducibility of biopsy grade in Sjögren's syndrome

The purpose of this study was to examine the reproducibility of biopsy grades at various tissue depths in Sjögren's syndrome. The biopsy grades of 38 minor salivary gland biopsies were examined at 6 microm, 50 microm, 100 microm, 150 microm, 200 microm, and 250 microm tissue depths. Tissue sections were stained with routine hematoxylin and eosin, graded I-IV, and compared with the initial "baseline" biopsy grade. The majority of the biopsies showed a wide range of grade variability at all depths. No tissue depth was consistently reproducible for any grade (P> or =0.41, 0.64, 0.91, and 0.20, respectively). The difference between baseline grades and grades of deeper sections was sufficient to impact the diagnosis of Sjögren's syndrome in approximately 60% of the biopsies (P<0.001). The overall result of this study suggests that examination of multiple sections of minor salivary gland biopsies is advisable to improve the reliability of the grade when evaluating Sjögren's syndrome.

Childhood oral pemphigoid: a case report and review of the literature

Oral pemphigoid, defined as cicatricial pemphigoid limited to the oral cavity, is a clinical subset of cicatricial pemphigoid. Like cicatricial pemphigoid, it occurs mostly in middle-aged women and it is uncommon in children under 20 years of age. There are 11 cases of childhood cicatricial pemphigoid published previously in the English language literature, and four of them are oral pemphigoid patients. We present a case of the youngest oral pemphigoid patient reported yet. Because of the rareness of cicatricial pemphigoid in children, delayed diagnosis and treatment have been shown in many cases reported earlier. Clinical awareness and early recognition are, therefore, emphasized.

Comparison of the oscillometric blood pressure monitor (BPM-100(Beta) ) with the auscultatory mercury sphygmomanometer

BACKGROUND

To compare directly the accuracy of the BPM-100(Beta) monitor (an automated oscillometric blood pressure device) with standard auscultatory mercury sphygmomanometry.

DESIGN

The BPM-100(Beta) was connected in parallel via a T-tube to a mercury sphygmomanometer. The BPM-100(Beta) and two trained observers (blinded from each other and from the BPM-100(Beta)) measured the sitting blood pressure simultaneously.

METHODS

Means, standard deviations and ranges were calculated for all the demographic data: age, arm size, heart rate and blood pressure. The agreement between the BPM-100(Beta) and the mean of two observers (the reference) was determined and expressed as the mean +/- SD, as well as the percentage of differences falling within 5, 10 and 15 mmHg.

RESULTS

Of the 92 subjects recruited, 85 (92.4%) met the inclusion criteria, and 391 sets of sitting blood pressure and heart rate measurements were available for analysis. The mean difference between the BPM-100(Beta) monitor and the reference was -0.62 +/- 6.96 mmHg for systolic blood pressure, -1.48 +/- 4.80 mmHg for diastolic blood pressure and 0.14 +/- 1.86 beats/min for heart rate. The only limitation of the device was its tendency to underestimate higher systolic blood pressures. This problem has been addressed by a minor change in the algorithm (see the companion publication, Blood Press Monit, 6, 161-165, 2001).

CONCLUSION

The BPM-100(Beta) is an accurate blood pressure monitor for the office setting, meeting all requirements of the Association for the Advancement of Medical Instrumentation and achieving an 'A' grade according to the British Hypertension Society protocol.

Validation of a new algorithm for the BPM-100 electronic oscillometric office blood pressure monitor

BACKGROUND

To test the accuracy of a new algorithm for the BPM-100, an automated oscillometric blood pressure (BP) monitor, using stored data from an independently conducted validation trial comparing the BPM-100(Beta) with a mercury sphygmomanometer.

DESIGN

Raw pulse wave and cuff pressure data were stored electronically using embedded software in the BPM-100(Beta), during the validation trial. The 391 sets of measurements were separated objectively into two subsets. A subset of 136 measurements was used to develop a new algorithm to enhance the accuracy of the device when reading higher systolic pressures. The larger subset of 255 measurements (three readings for 85 subjects) was used as test data to validate the accuracy of the new algorithm.

METHODS

Differences between the new algorithm BPM-100 and the reference (mean of two observers) were determined and expressed as the mean difference +/- SD, plus the percentage of measurements within 5, 10, and 15 mmHg.

RESULTS

The mean difference between the BPM-100 and reference systolic BP was -0.16 +/- 5.13 mmHg, with 73.7% < or = 5 mmHg, 94.9% < or = 10 mmHg and 98.8% < or = 15 mmHg. The mean difference between the BPM-100 and reference diastolic BP was -1.41 +/- 4.67 mmHg, with 78.4% < or = 5 mmHg, 92.5% < or = 10 mmHg, and 99.2% < or = 15 mmHg. These data improve upon that of the BPM-100(Beta) and pass the AAMI standard, and 'A' grade BHS protocol.

CONCLUSION

This study illustrates a new method for developing and testing a change in an algorithm for an oscillometric BP monitor utilizing collected and stored electronic data and demonstrates that the new algorithm meets the AAMI standard and BHS protocol.

The 2000 Canadian recommendations for the management of hypertension: Part one--therapy

OBJECTIVE

To provide updated, evidence-based recommendations for the therapy of hypertension in adults.

OPTIONS

For patients with hypertension, there are a number of lifestyle manoeuvres and antihypertensive agents that may control blood pressure. Randomized trials evaluating first- line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed.

OUTCOMES

The health outcomes considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence.

EVIDENCE

Medline searches were conducted from the period of the last revision of the Canadian Recommendations for the Management of Hypertension (May 1998 to October 2000). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and mortality.

BENEFITS, HARMS, AND COSTS

Various lifestyle manoeuvres and antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality.

RECOMMENDATIONS

The present document contains detailed recommendations pertaining to all aspects of the therapy of patients with hypertension, including lifestyle modifications proven to lower blood pressure, treatment thresholds, target blood pressures, choice of agents in various settings and strategies to enhance adherence. Lower thresholds for blood pressure treatment are advocated for people with other cardiovascular risk factors or established hypertensive target organ damage. Implicit in the recommendations for therapy is the principle that treatment should be individualized for each patient and the choice of agent should be dictated by coexistent conditions. For the treatment of uncomplicated essential hypertension, thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors or calcium channel blockers may be appropriate, depending on individual circumstances.

VALIDATION

All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported here. These guidelines will be updated annually.

Target-Directed Enediynes: Designed Estramycins

The goal of selective targeting of enediyne cytotoxins has been investigated using estrogenic delivery vehicles. A series of estrogen-enediyne conjugates were assembled, and affinity for human estrogen receptor [hERalpha] was determined. The most promising candidate induced receptor degradation following Bergman cycloaromatization and caused inhibition of estrogen-induced transcription in T47-D human breast cancer cells.

Bone density adjacent to press-fit acetabular components. A prospective analysis with quantitative computed tomography

BACKGROUND

The status of periprosthetic bone stock is an important concern when revision total hip arthroplasty is undertaken. Remodeling of periprosthetic femoral bone after total hip arthroplasty has been studied extensively, and the phenomenon of femoral stress-shielding has been well characterized. Finite element analysis and computer-simulated remodeling theory have predicted that retroacetabular bone-mineral density decreases after total hip arthroplasty; however, remodeling of periprosthetic pelvic bone in this setting has yet to be well defined. This study was conducted to evaluate the short-term natural history of periacetabular bone-mineral density following primary total hip arthroplasty.

METHODS

Periacetabular bone-mineral density was studied prospectively in a group of twenty-six patients who underwent primary hybrid total hip arthroplasty for the treatment of advanced osteoarthritis. Density within the central part of the ilium (directly cephalad to a press-fit acetabular component) was assessed with serial quantitative computed tomography. Baseline density was measured within the first five days following the total hip arthroplasty. Ipsilateral density measurements were repeated at an average of 1.28 years postoperatively. Density values at corresponding levels of the contralateral ilium were obtained at both time-points in all patients to serve as internal controls.

RESULTS

Bone-mineral density decreased significantly (p< or =0.001) between the two time-points on the side of the operation. The mean absolute magnitude of the interval density reduction (75 mg/cc) was greatest immediately adjacent to the implant (p<0.001), but it was also significantly reduced (by 35 mg/cc) at a distance of 10 mm cephalad to the implant (p = 0.001). Relative declines in mean density ranged from 33% to 20% of the baseline values. No focal bone resorption (osteolysis) was detected at the time of this short-term follow-up study. With the numbers available, no significant interval alteration in bone-mineral density was found on the untreated (internal control) side (p> or =0.07).

CONCLUSIONS

We suggest that the observed decline in bone-mineral density represents a remodeling response to an altered stress pattern within the pelvis that was induced by the presence of the acetabular implant. This finding corroborates the predictions of finite element analysis and computer-simulated remodeling theory. It remains to be seen whether this trend of atrophy of retroacetabular bone stock will continue with longer follow-up or will ultimately affect the long-term stability of press-fit acetabular components.