DBP formation kinetics in a simulated distribution system.

Little is known about how the growth of halogenated disinfection by-products (DBPs) in drinking water is affected by time spent in a distribution system. Experiments were performed to compare the rate of trihalomethane and haloacetic acid production in a simulated pipe environment to that observed for the same water held in glass bottles. Results showed that although the rate of chlorine consumption in the pipe was much greater than in the bottle, there was no decrease in the amount of haloacetic acids produced and that trihalomethane levels actually increased by an average of 15%. Separate tests confirmed that this increase was due to a reservoir of organic precursor material associated with deposits on the pipe wall. This work suggests that the rate of DBP production in a distribution system will not necessarily be reduced by increased chlorine consumption due to non-DBP producing reactions with deposits on the pipe wall.

The emergency department presentation of patients with active pulmonary tuberculosis.

OBJECTIVE: To determine the clinical presentation of emergency department (ED) patients with active pulmonary tuberculosis (TB). METHODS: This was a retrospective medical record review of adult patients, identified through infection control records, diagnosed as having active pulmonary TB by sputum culture over a 30-month period at an urban teaching hospital. The ED visits by these patients from one year before to one year after the initial positive sputum culture were categorized as contagious or noncontagious, using defined clinical and radiographic criteria. The medical records of patients with contagious visits to the ED were reviewed to determine chief complaint, presence of TB risk factors and symptoms, and physical examination and chest radiograph findings. RESULTS: During the study period, 44 patients with active pulmonary TB made 66 contagious ED visits. Multiple contagious ED visits were made by 12 patients (27%; 95% CI = 15% to 43%). Chief complaints were pulmonary 33% (95% CI = 22% to 46%), medical but nonpulmonary 41% (95% CI = 29% to 54%), infectious but nonpulmonary 14% (95% CI = 6% to 24%), and traumatic/orthopedic 12% (95% CI = 5% to 22%). At least one TB risk factor was identified in 57 (86%; 95% CI% = 76 to 94%) patient visits and at least one TB symptom in 51 (77%; 95% CI = 65% to 87%) patient visits. Cough was present during only 64% (95% CI = 51% to 75%) of the patient visits and hemoptysis during 8% (95% CI = 3% to 17%). Risk factors and symptoms that, if present, were likely to be detected at triage were foreign birth, homelessness, HIV positivity, hemoptysis, and chest pain. CONCLUSIONS: Patients with active pulmonary TB may have multiple ED visits, and often have nonpulmonary complaints. Tuberculosis risk factors and symptoms are usually present in these patients but often missed at ED triage. The diversity of clinical presentations among ED patients with pulmonary TB will likely make it difficult to develop and implement high-yield triage screening criteria.

Defecation-induced bronchospasm.

Acute asthma exacerbations are common. Patients with asthma experience symptoms in response to a wide variety of stimuli, and identifying the precipitating cause may be useful in guiding treatment and preventing future attacks. A case of asthma exacerbation occurring during multiple defecations is reported. Abnormal parasympathetic tone has been implicated in the pathogenesis of certain types of asthma, and defecation can be associated with increased parasympathetic tone. This patient's pattern of defecation-related asthma exacerbations responded to prophylactic anticholinergic medication.

Feasibility of laparoscopic cholecystectomy with miniaturized instrumentation in 50 consecutive cases.

A new technique utilizing miniaturized (2 mm) instrumentation to perform laparoscopic cholecystectomy (LC) is introduced. The safety and efficacy of this mini-LC were assessed. Fifty consecutive mini-LCs were performed using one 10-mm port and three 2-mm ports (cumulative port size 16 mm). A 2-mm fiberoptic video-laparoscope was placed in the mid-epigastrium through a 2-mm port. A 10-mm umbilical port was then placed under direct visualization, allowing access for standard laparoscopic instruments. Two additional 2-mm ports were placed in the right upper quadrant allowing insertion of grasping instruments. Parameters reviewed included total operative time (OT), postoperative length of stay (LOS), anatomic pathology, complications, and rate of conversion to conventional LC and open cholecystectomy. Results were compared to those of 50 consecutive conventional LCs using two 10-mm and two 5-mm ports (cumulative port size 30 mm). The OT for the mini-LC and conventional LC were 88 +/- 5.9 and 78 +/- 5 minutes (mean +/- SD), respectively, (p = NS), and postoperative LOS for the mini-LC and conventional LC were 1.5 +/- 0. 2 and 1.8 +/- 0.4 days (mean +/- SD), respectively, (p = NS). Of the 50 mini-LC cases, 5 required conversion to conventional LC. One cystic duct leak was detected and successfully treated conservatively; no common bile duct injuries occurred; and no patients required conversion to open cholecystectomy. This study demonstrates the safety and efficacy of minilaparoscopic instruments for the performance of cholecystectomy. The data reveal that this new technique is comparable to conventional LC.

The sterilization of endodontic hand files.

Several different methods of file sterilization were analyzed to determine the best method of providing complete file sterility, including the metal shaft and plastic handle. Six test groups of 15 files were studied using Bacillus stearothermophilus as the test organism. Groups were "sterilized" by glutaraldehyde immersion, steam autoclaving, and various techniques of salt sterilization. Only proper steam autoclaving reliably produced completely sterile instruments. Salt sterilization and glutaraldehyde solutions may not be adequate sterilization methods for endodontic hand files and should not be relied on to provide completely sterile instruments.

Intentional replantation of endodontically treated teeth.

This article reports 31 cases of intentional replantation with an overall success rate of 80.6% with six recorded failures. Survival times varied from 1 day to 22 years. A second mandibular molar that failed after 3 weeks was replanted successfully a second time with no signs of failure after a 46-month follow-up period. Two cases of intentional replantation of deciduous molars are also reported. We suggest that intentional replantation reduces adverse outcomes and should be considered as another treatment modality and not as a procedure of last resort. This procedure is recommended as the treatment of choice in the following instances: for lower second molars, for single-rooted teeth, and lower first molars when there is difficulty in accessibility to perform apical surgery; when the mental foramen is superimposed over the apex of the premolars; when the molar apex is in proximity to the mandibular canal; when patients object to periradicular surgery; when failures occur after apical surgery, or when surgery would create a periodontal pocket as a result of extensive bone removal. Periradicular surgery with a retroseal is more advantageous for first molars when roots are more curved, widespread, and are more prone to fracture compared with second molars whose roots are more tapered and close together.

Biological effect of bright light.

1. Five minute bright light exposures reduced plasma levels of melatonin in eight normal subjects. 2. No significant change in ACTH levels occurred. 3. These results raise the possibility that short intense light exposures can synchronize circadian rhythms as well as benefit patients with seasonal affective disorder. They also indicate that short pulses of bright light do not affect pituitary ACTH production.

Effect of 64-hour sleep deprivation on the circadian waveform of thyrotropin (TSH): further evidence of sleep-related inhibition of TSH release.

Half-hourly sampling of plasma TSH was done across 3 days in four normal young men. Sleep was denied for 64 h from 0700 h on awakening from accommodation sleep until polygraphic sleep was resumed at 7100 h of the third day (D3) such that 2 consecutive nights of usual 2300-0700 h sleep were missed. This protocol allowed examination of any modulatory effects on the daily patterns in TSH concentrations during sleep deprivation on D1-2 (1100-3500, 3500-5900 h) or during resumption of usual nightly sleep on D3 (5900-8300) compared to that of a previously studied group of normal young men. The circadian nature of the daily TSH waveform was evidenced by its daily repetition within a subject both basally and during D1-2 sleep deprivation and by its synchronization within the basal, deprived, or resumed sleep days. The peaks in each subject's daily TSH patterns on D1-2 were consistently longer, and the daily maxima and cosine acrophases on D1-2 were consistently later than those on D3 when basal sleep was resumed. About half the daily TSH concentration maxima and daily cosinor amplitudes on D1-2 were greater than those of the respective sleep-resumed TSH patterns of D3. Both the group mean TSH patterns and the cosinor 95% confidence ellipses also indicated the daily peak in the TSH waveform to be significantly longer, later, and larger during D1-2 sleep deprivation than during the basal or D3 periods. These results indicate that significant alteration of the daily TSH waveform can occur in response to absence of sleep and are compatible with the existence of an inhibitory effect in early nightly sleep on TSH release. The TSH patterns during the 1700-2300 h intervals of rising TSH levels were congruent in the basal, deprived, and resumed sleep periods. Prompt reversion to the basal TSH pattern also occurred when sleep was resumed on D3. Both of these observations suggest the alteration in TSH waveform during sleep deprivation to have arisen from an inhibitory effect in sleep rather than from a change in period or phase of a generating oscillator.

Ethanol-related prolactin responses and risk for alcoholism.

Serum prolactin (PRL) levels after drinking 0.75 ml/g of ethanol were observed in 44 nonalcoholic young men who had an alcoholic first-degree relative and 44 controls lacking a family history of alcoholism. The data reveal a significant increase in PRL by 30 min with a return to base line for the family history negative (FHN) men by 90 min but a further decline until 150 min for the family history positive (FHP) individuals. The interaction between family history status and time for prolactin was significant at the p = 0.008 level and the changes in this hormone after drinking was significant for both groups at the p less than 0.0001 level. These results are consistent with an effect of a moderate dose of ethanol on PRL levels and further characterize differences in reactions to ethanol for men at higher and lower risk for the future development of alcoholism.

Sleep-associated gonadotrophin and oestradiol patterns in girls with precocious sexual development.

Circulating concentrations of gonadotrophins and oestradiol (E2) during sleep were examined in six girls aged 5-10 years with precocious sexual development. All subjects exhibited nocturnal increments of LH and/or FSH. Gonadotrophin secretion appeared to vary from pulsatile release to random oscillations. Three subjects with LH pulses of greater than 5 miu/ml and a concomitant FSH rise had a temporal elevation of E2 during sleep. The other three subjects with pulses of either LH or FSH of less than 5 miu/ml had no nocturnal rise in E2. These data suggest that the nocturnal elevation of E2 results from pituitary release of both LH and FSH, leads to premature sexual development, and may be occasioned by inappropriate timing of hypothalamic gonadotrophin-releasing hormone (LHRH) secretion.

Biosynthesis of collagen in isolated periodontal ligament.

This study showed that the excised periodontal ligament from humans and hamsters actively synthesizes protein, as measured by 14C-proline incorporation, when incubated in vitro for periods of 30 minutes to six hours. However, only a small percentage of the protein synthesized was collagen.