Influence of carbon and buffer amendment on ammonia volatilization in composting.

Laboratory-scale experiments were carried out to test a mathematical model of the nitrogen dynamics in a composting process. The main ingredients of composting materials were wheat straw and dairy manure. The influence of (a) two carbon amendments, i.e. molasses and office paper, and (b) two chemicals forming buffer solutions on ammonia volatilization were investigated. Nitrogen losses amounted to 12-25% of initial nitrogen, in which ammonia volatilization accounted for 60-99%. Addition of molasses, a readily available form of carbon, reduced cumulative ammonia emissions substantially, but office paper, i.e. cellulose, had only a small influence. The addition of buffering chemicals did not significantly reduce ammonia volatilization.

Relationship between water repellency and native and petroleum-derived organic carbon in soils.

Some soils develop severe and persistent water repellency following contamination with crude oil. This study was conducted to characterize and compare the spatial distribution of soil water repellency and residual oil contamination at 12 such sites. The molarity of ethanol droplet (MED) test was used to assess soil water repellency and the content of dichloromethane-extractable organics (DEO) was used to quantify residual oil in soil. We found a relatively strong positive correlation between MED and DEO in soil (r2 = 0.74). Both variables tended to decrease abruptly with depth at 11 of the 12 study sites. Dichloromethane-extractable organics similarly decreased with depth in control adjacent soil (MED = 0 M), but from an average concentration one to two orders of magnitude lower than in water-repellent soil. Using data from corresponding control adjacent and water-repellent soils, we determined that approximately 29 and 10% of measured total organic carbon in water-repellent A- and B-horizon soil, respectively, consists of dichloromethane-insoluble organic carbon of petroleum origin. We propose that this fraction contains most of the causative agents of soil water repellency at the studied sites.

Acute ecotoxicity of creosote-contaminated soils to Eisenia fetida: a survival-based approach.

Quantification of risks to the ecosystem is necessary for cost-effective remediation strategies. Contaminant endpoints need to be established that consider the bioavailability of toxicants in soil. The challenge is to develop methods that assign risk to the bioavailable toxic contaminants, thereby protecting ecosystems, while balancing remediation costs. Our objective was to evaluate changes in bioavailability of creosote constituents in soils to earthworms. An acute ecotoxicological investigation of three weathered creosote-contaminated and two slurry-phase-biotreated soils was conducted using a 14-d earthworm (Eisenia fetida) survival bioassay. Soil characterization (physical and chemical) and contaminant concentration data (polycyclic aromatic hydrocarbons [PAH] and total dichloromethane extractable organics [DEO]) were also determined. The toxicity of the soils could not always be predicted based on chemical concentrations alone. Soils having a low PAH:DEO ratio had higher cumulative earthworm survival times as measured by earthworm-days. We propose that the DEO fraction may regulate toxicity by altering bioavailability of toxicants.

Sorption of 1-naphthol to soil and geologic samples with varying diagenetic properties.

Remediation of contaminated land requires a firm understanding of the processes that occur between xenobiotics and soil colloids. It is currently accepted that the extent of xenobiotic uptake is proportional to the carbon quantity and character of the soil or geologic sample. Previous studies have developed empirical equations to predict the extent of sorption based on the aromatic carbon content. We examined these relationships with an independent set of soil and geologic samples and 1-naphthol. The 1-naphthol sorption coefficients varied significantly (P < 0.01) among sorbents and are consistent with the diagenetic properties of the organic matter in these samples. The cross-polarization magic angle spinning (CPMAS) 13C nuclear magnetic resonance (NMR) and elemental data did not concur with the sorption data for most of the soil samples. We suggest that this contradiction may be due to a third variable, the physical organization of the organic matter. Chemical methods measure the whole sample, whereas short-term sorption occurs on the surface; therefore, only some organic matter domains in the soil are available for interaction with 1-naphthol. Hence, chemical data alone may be insufficient for predicting the sorption behavior of xenobiotics in soil and geologic samples.

Comparison of three techniques for internal jugular vein cannulation in infants.

Central venous cannulation allows accurate monitoring of right atrial pressure and infusion of drugs during the anaesthetic management of infants undergoing cardiopulmonary bypass. In this prospective, randomized study, we compared the success and speed of cannulation of the internal jugular vein in 45 infants weighing less than 10 kg using three modes of identification: auditory signals from internal ultrasound (SmartNeedle, SM), external ultrasound imaging (Imaging Method, IM) and the traditional palpation of the carotid pulsation and other landmarks (Landmarks Method, LM). The cannulation time, number of attempts with LM and SM techniques were greater than those with IM technique. The incidence of carotid artery puncture and the success rate were not significantly different among the three groups. In infants, a method based on visual ultrasound identification (IM) of the internal jugular vein is more precise and efficient than methods based on auditory (SM) and tactile perception (LM).

Ultrasound-guided internal jugular venous cannulation in infants: a prospective comparison with the traditional palpation method.

BACKGROUND: Percutaneous cannulation of the internal jugular vein in infants is technically more difficult and carries a higher risk of carotid artery puncture than in older children and adults. In this prospective study, the authors tested their hypothesis that using an ultrasound scanner would increase the success of internal jugular cannulation and decrease the incidence of carotid artery puncture in infants. METHODS: After approval from the institutional review board and receipt of written informed parental consent, 95 infants scheduled for cardiac surgery were randomized prospectively into two groups. In the landmarks group, the patients' internal jugular veins were cannulated using the traditional method of palpation of carotid pulsation and identification of other anatomic landmarks. In the ultrasound group, cannulation was guided using an ultrasound scanner image. The cannulation time, number of attempts, success rate, and incidence of complications were compared for the two groups. RESULTS: There were no significant differences between the two groups with regard to weight, age, and American Society of Anesthesiologists physical status classification. The success rate was 100% in the ultrasound group, with no carotid artery punctures, and 77% in the landmarks group, with a 25% incidence of carotid artery punctures. Both differences were significant (P > 0.0004). The cannulation time was less, the number of attempts was fewer, and the failure rate was significantly lower in the ultrasound group than in the landmark group. CONCLUSION: Ultrasonographic localization of the internal jugular vein was superior to the landmarks technique in terms of overall success, speed, and decreased incidence of carotid artery puncture.

Pap smear screening in an urban STD clinic. Yield of screening and predictors of abnormalities.

BACKGROUND: Pap smear screening studies in STD clinics have reported high rates of squamous intraepithelial lesions (SIL); however, there are limited data on levels of unsatisfactory smears of characteristics associated with cytologic abnormalities. GOAL: To assess the yield to Pap smear screening in an STD clinic and to evaluate the rates of and risk factors for atypia, low-grade SIL (LSIL), and high-grade SIL (HSIL). STUDY DESIGN: A chart review of the clinic records of women undergoing Pap smear screening between 1991 and 1994 was conducted. Results were assessed from two different screening protocols, the first using a Dacron swab to obtain the endocervical sample and the second using a cytobrush. RESULTS: Of 2034 Pap smears, 1313 (64.6%) were negative, 202 (9.9%) were unsatisfactory, 257 (12.6%) were atypical, 211 (10.4%) had LSIL, and 51 (2.5%) had HSIL. With the change to the cytobrush protocol, the rate of unsatisfactory smears decreased from 14.4% to 3% (p < 0.001), atypia increased from 10% to 16.7% (p < 0.001), and HSIL rose from 1.7% to 3.7% (p < 0.001). By multivariate analysis, atypia was associated with genital warts (odds ratio (OR) 1.53, 95% confidence interval (CI): 1.16-2.02); LSIL with younger age (p < 0.001, for trend), black race (OR 1.51, 95% CI: 1.08-2.10), genital warts (OR 1.81, 95% CI: 1.33-2.47), and an abnormal appearance of the cervix on examination (OR 2.49, 95% CI: 1.85-3.35); and HSIL with a previous abnormal Pap smear (OR 2.48, 95% CI: 1.08-2.10). Overall, abnormality rates were significantly higher in adolescents (35.5%) than older women (21.7%) (p < 0.01). CONCLUSIONS: Obtaining satisfactory Pap smears among women undergoing screening in an STD clinic is feasible and cytologic abnormalities are common. These results continue to support the need for Pap smear screening in STD clinics, but the high rates in adolescents, a group in whom the natural history of cytologic abnormalities has not been well-defined, raise questions about the need to develop age-appropriate screening and management strategies.

Prevalence of human immunodeficiency virus infection, mortality rate, and serogroup distribution among patients with pneumococcal bacteremia at Denver General Hospital, 1984-1994.

Pandemics of human immunodeficiency virus (HIV) type 1 infection and penicillin resistance highlight the urgency of preventing invasive pneumococcal disease with vaccination. We characterized pneumococcal serogroup distribution and the mortality rate among 460 patients with pneumococcal bacteremia from 1984 through 1994 at Denver General Hospital and the prevalence of HIV infection in patients for whom pneumococcal bacteremia was diagnosed from 1989 to 1994. Vaccine-related serogroups accounted for 426 isolates (92.6%), including 48 (92.3%) of 52 isolates from HIV-infected patients. Mortality among patients 15 years of age or older was higher during 1984-1988 (18[12.9%] of 140) than during 1989-1994 (10 [5.2%] of 191: rate ratio, 2.5; 95% confidence interval, 1.2-5.2). Of patients 15-59 years of age from 1989 to 1994, 44 (39.6%) of 111 men and three (7.3%) of 41 women were HIV-infected. Four (8.5%) of 47 HIV-infected patients and four (3.8%) of 105 other patients in this group died (age-weighted rate ratio, 1.8; 95% confidence interval, 0.5-6.2). We recommend routine screening of young adults with pneumococcal bacteremia for HIV infection and immunization of HIV-infected patients with pneumococcal vaccine (which includes most serogroups of infecting strains).

Site and extent of mineral absorption in lactating cows fed whole-crop cereal grain silage of alfalfa silage.

The site of apparent absorption of Na, K, Ca, P, Mg, and S in lactating dairy cows fed whole-crop barley, oats, triticale, or alfalfa silages was studied. Eight ruminally and duodenally cannulated Holstein cows with ad libitum access to a total mixed diet were assigned to one of four treatments as a replicated 4 x 4 Latin square design. All diets contained the same concentrate (50%, DM basis) plus one experimental silage. The concentrations of Na, K, Ca, P, Mg, and S in the concentrate were .84, .71, .85, .78, .27, and 38%, respectively. Dry matter intake was higher (P < .05) for cows fed alfalfa and barely silages than for cows fed oats and triticale silages (19.6, 18.6, 16.7, and 17.2 kg/d, respectively). Alfalfa silage contained a higher concentration of all minerals studied than the cereal silages, except Na. Sodium flow at the duodenum was substantially greater than dietary intake and apparent total tract digestibilities ranged between 74.5 and 85.2%. Secretion of P in the forestomach ranged from 34 to 61 g/d and the major site of absorption was in the intestine. The correlation between P intake and fecal excretion of P was significant (P < .001, r/ = .39) and linear. Potassium absorption occurred before the duodenum and in the intestine. Apparent digestibilities of K were lower for cereal silages (range 74.0 to 82.9%) than for alfalfa silage (88,7%). Apparent total tract digestibilities of Ca (28 to 32%), P(27 to 34%), and MG (17 to 24%) were similar for all diets so that Ca, P, and Mg absorption (g/d) reflected dietary Ca, P, and Mg levels. Data indicate that forage source can influence the site and extent of absorption, fecal output, and apparent digestibilities of macrominerals.

Usefulness of human immunodeficiency virus post-test counseling by telephone for low-risk clients of an urban sexually transmitted diseases clinic.

BACKGROUND: Failure of clients to return for post-test counseling for human immunodeficiency virus (HIV) has been noted consistently as a problem with HIV counseling and testing in sexually transmitted disease clinics. GOALS: To assess trends in the rates of HIV post-test counseling in an urban sexually transmitted disease clinic. To determine the usefulness of providing post-test counseling by telephone to clients at low risk for HIV as a means of increasing post-test counseling rates and efficiency of clinic operations. STUDY DESIGN AND METHODS: Human immunodeficiency virus post-test counseling rates were evaluated among clients of a sexually transmitted disease clinic from January 1990 through May 1994. Low-risk clients (n = 1,304) from July 1994 through September 1994 were given the option of obtaining negative HIV test results by telephone. Rates of post-test counseling within 45 days were compared with historical controls from March 1994 through May 1994, during which time a return visit was required. RESULTS: The rate of post-test counseling increased significantly from 1990 to 1992 but remained stable thereafter. After the introduction of post-test counseling by telephone, 704 of 1,304 low-risk clients (54.0%) obtained post-test counseling compared with 476 of 1,187 (40.1%) clients during the control period (odds ratio = 1.75; 95% confidence interval = 1.50-2.06). Post-test counseling rates increased especially among clients younger than 20 years of age (30.6% versus 52.7%) and among those with multiple new sex partners in the last month (31.6% versus 56.1%). CONCLUSIONS: Telephone post-test counseling is an effective method of increasing access for low-risk clients attending sexually transmitted diseases clinics and may be especially useful for those who are otherwise unlikely to obtain post-test counseling.

Age and the onset of desaturation in apnoeic children.

Most patients undergoing general anaesthesia are apnoeic during laryngoscopy and tracheal intubation. This study determined the time until the onset of desaturation following pre-oxygenation in apnoeic infants, children, and adolescents. Fifty ASA physical status I patients, 2 days to 18 yr of age, were studied. The patients were stratified into one of five groups according to age: Group I, 0-6 mo; Group II, 7-23 mo; Group III, 2-5 yr; Group IV, 6-10 yr; and Group V, 11-18 yr. Following induction of anaesthesia with halothane via mask or intravenous barbiturates, the ability of the anaesthetist to ventilate the lungs via the mask was ascertained and paralysis was accomplished with vecuronium 0.1 mg.kg-1. Manual mask ventilation was maintained with oxygen and halothane. When end-tidal N2 decreased below 3% (minimum time two minutes), the face mask was removed. The time between the removal of the face mask and a decrease in oxygen saturation (SpO2) from 99-100% to 90% was measured. Manual ventilation was then resumed and the trachea intubated. Desaturation started earlier in infants than in two- to five-year-old children (96.5 +/- 12.7 sec vs 160.4 +/- 30.7 sec, P < 0.0001). Children became desaturated faster than adolescents (160.4 +/- 30.7 vs 382.4 +/- 79.9 sec, P < 0.0001). The time required to reach 90% saturation correlated well with age by linear regression analysis (r2 = 0.88, P < 0.0001). We conclude that the time to onset of desaturation following pre-oxygenation with mask ventilation increases with age in healthy apnoeic children.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction and maintenance characteristics of anesthesia with desflurane and nitrous oxide in infants and children.

To determine the induction and maintenance characteristics of desflurane in pediatric patients, the authors anesthetized 206 infants and children aged 1 month to 12 yr with nitrous oxide plus desflurane and/or halothane in oxygen. Patients were assigned to one of four groups: anesthesia was 1) induced and maintained with desflurane after premedication with an oral combination of meperidine, diazepam, and atropine; 2) induced and maintained with desflurane; 3) induced with halothane and maintained with desflurane; or 4) induced and maintained with halothane. An unblinded observer recorded time to loss of consciousness (lid reflex), time to intubation, and clinical characteristics of the induction and maintenance of anesthesia. Moderate-to-severe laryngospasm (49%) and moderate-to-severe coughing (58%) occurred frequently during induction of anesthesia with desflurane; the incidence of these was not altered by premedication. In contrast, laryngospasm and coughing were rare during induction of anesthesia with halothane. In unpremedicated patients, time to loss of lid reflex (mean +/- SD) was similar for desflurane (2.4 +/- 1.2 min) and halothane (2.1 +/- 0.8 min). During induction of anesthesia, before laryngoscopy and intubation, mean arterial pressure less than 80% of baseline was more common with halothane; heart rate and mean arterial pressure greater than 120% of baseline were more common with desflurane. Intraoperatively, heart rate greater than 120% of baseline was more common with desflurane; blood pressures were similar for the two anesthetics. The authors conclude that the high incidence of airway complications during induction of anesthesia with desflurane limits its utility for inhalation induction in pediatric patients. Anesthesia can be safely maintained with desflurane if induced with a different anesthetic.

Propofol: effective dose and induction characteristics in unpremedicated children.

The induction dose, induction characteristics, and cardiovascular and respiratory effects of propofol were studied in 90 unpremedicated children 3-12 yr old. Propofol in a dose of 1-3 mg.kg-1 was injected in an antecubital vein over 10-30 s. Successful induction was defined by loss of eyelash reflex occurring within 50 s of the conclusion of propofol injection and followed by subsequent acceptance of face mask without excessive movement. The effective dose of propofol resulting in loss of eyelash reflex in 50% (ED50) and 95% (ED95) of children were 1.3 (1.1-1.4) and 2.0 (1.7-2.6) mg.kg-1 (95% confidence interval). The corresponding ED50 and ED95 for a successful induction that included acceptance of face mask were 1.5 (1.3-1.7) and 2.3 (2.1-3.0), respectively. There was a 6.6% incidence of mild to moderate pain on injection and a 12.7% incidence of involuntary movement. Apnea (cessation of breathing greater than 20 s) was seen in 21% of patients. Blood pressure decreased by more than 20% of baseline value in 48% of patients who received halothane (1-3%) after the bolus injection of propofol. It is concluded that propofol is an effective induction agent in children. A dose of 2.5-3.0 mg.kg-1 is recommended to ensure a smooth transition to an inhalational maintenance technique. The use of antecubital veins is associated with a low incidence of pain on injection.