Spectroscopic determination of open complex formation at promoters for Escherichia coli RNA polymerase

A considerable amount of effort has been expended studying the kinetics of association of Escherichia coli RNA polymerase with promoter DNA in forming the open complex. Strand separation occurs over about 12 base pairs and includes the transcription start site. However, these efforts have been significantly hampered by the lack of a sensitive, real time method by which formation of an open complex could be assayed. Here, we employ short (86 bp) synthetic promoters with 2-aminopurine (2-AP) substitutions in the region that becomes single-stranded to spectroscopically monitor open complex formation. We demonstrate that promoters bearing the substitutions behave in a manner similar to that of those containing only the four common bases with respect to both the region of strand separation and start site selection. Open complex formation was found to yield an increased fluorescence signal with an emission maximum characteristic of 2-aminopurine. This spectroscopic assay for open complex formation was found to be well-suited to the investigation of a strong promoter, allowing open complex formation to be followed over a time scale of seconds with a stopped flow apparatus. The introduction of two additional nonconsensus base pairs in the -35 region resulted in a promoter for which open complex formation was 100-fold slower. The same substrates were also used to monitor the promoter re-annealing that ensues upon initiation of RNA synthesis. Similar rates for this process were observed for the two promoter variants employed in this study.

Keratoacanthoma: the Australian experience

Comment is offered on the roughly 50 years experience of Australian clinicians with the various types of keratoacanthoma, and local contributions to knowledge in this area is indicated. The higher incidence in warmer areas, with consequent early acceptance of the entity, is documented. Effects of immunosuppression are recorded, and viral and immunological studies noted. Aspects of special sub-groups, such as multiple and subungual, and of treatment, are briefly discussed, and future areas of research mentioned.

The effect of exercise induced glycogen depletion on the lactate, ventilatory and electromyographic thresholds

BACKGROUND

This study compared the integrated electromyogram (IEMG), lactate, and ventilatory thresholds under normal glycogen (NG) and depleted glycogen (DG) conditions for the purpose of determining the presence of a possible relationship between neuromuscular, metabolic and respiratory thresholds.

MATERIALS AND METHODS

Six trained, male cyclists (Age = 24.0 +/- 2.45 yrs, Ht = 1.76 +/- 0.84 m, Mass = 76.22 +/- 10.03 kg, % Fat = 8.57 +/- 1.50, VO2 peak = 68.97 +/- 10.46 ml . kg-1 . min-1) completed a progressive, incremental cycle ergometer test under NG and DG conditions in a randomized order. Glycogen depletion was accomplished by having the subjects: (1) engage in a 12 hour fast prior to the exercise test, (2) complete a 1.5 hour ride at their ventilatory threshold, and (3) complete 4 to 8 one-minute rides at 100% of VO2 peak. Six hours following the depletion rides, the subjects completed the exercise test (90 rpm, 45 watts/2 min). Blood was withdrawn through a forearm venous catheter each minute and later analyzed for blood lactate. Metabolic data were measured every 30s and the IEMG of the rectus femoris was recorded during the last 10s of each minute of the exercise test. Results showed that under NG, the IEMG (TIEMG), lactate (Tlac), and ventilatory (Tvent) thresholds occurred at a similar VO2 (TIEMG = 3.46 +/- 0.31, Tlac = 3.51 +/- 0.34, Tvent = 3.36 +/- 0.42 L . min-1). However, under DG there was a significant shift in the TIEMG to a higher VO2 (TIEMG = 4.41 +/- 0.54 L . min-1 = p 0.003). Tlac was not significantly greater following glycogen depletion, but had shifted to a higher VO2 in relation to the Tvent (Tlac = 3.96 +/- 0.40 L . min-1, Tvent = 3.37 +/- 0.64 L . min-1 = p 0.01). These data show that lactate accumulation and muscle activation of the vastus lateralis and rectus femoris are not the controlling mechanisms of the ventilatory threshold during progressive, incremental cycling exercise.

Schistosomiasis in Lake Malawi

BACKGROUND

In 1992 two US Peace Corps volunteers (PCVs) developed central nervous system schistosomiasis due to infection with Schistosoma haematobium following recreational water exposure at Cape Maclear on Lake Malawi, an African lake considered by many to be free of schistosomiasis. To determine the transmission potential and risk for aquiring schistosomiasis in Lake Malawi, a cross-sectional survey of resident expatriates and visitors to Malawi was done during March and April, 1993.

METHODS

A volunteer cohort of expatriates and visitors representing a cross-section of Malawi's foregn population answered detailed questions about freshwater contact and provided blood specimens to determine the seroprevalence of S haematobium and S mansoni by ELISA and immunoblot analyses. A survey for vector snails was conducted along Lake Malawi's southwestern shore.

FINDINGS

The study population of 955 included 305 US citizens and 650 non-US foreign nationals. 303 of the study population had serological evidence of current or past schistosome infection. Seroprevalence was 32% (141/440) among expatriates whose freshwater exposure was limited to Lake Malawi; S haematobium antibodies were found in 135 of 141 (96%) seropositive specimens. Risk of seropositivity increased with the number of freshwater exposures at Lake Malawi resorts. Although many resort areas in the southwestern lake region posed a significant risk, Cape Maclear was the location most strongly associated with seropositivity (OR 2.9, 95% Cl 1.6-5.1). Schistosome-infected Bulinus globosus, the snail vector of S haematobium in Malawi, were found at Cape Maclear and other locations along the lakeshore.

INTERPRETATION

S haematobium infection is highly prevalent among expatriates and tourists in Malawi. Recreational water contact at popular resorts on Lake Malawi is the most likely source of infection. Transmission of schistosomiasis is occurring in Lake Malawi, a previously under-recognised site of transmission.

Return to work as a measure of outcome in adults hospitalized for acute burn treatment

Rehabilitation of patients with burn injuries is receiving renewed interest because survival has improved, and health reform has mandated outcomes assessment. To determine factors affecting return to work, a survey was conducted among 234 employed patients treated from 1986 through 1993. The mean burn size was 13.3% total body surface area. Patients returned to work in a mean of 14.3 weeks; a number initially returned to light-duty or part-time jobs as a "bridge" to full-time employment. Length of hospitalization, number of surgeries, total and full-thickness burn size, and subjective assessments by patients of their functional ability correlated with time off work. Patients with health insurance were more likely to resume work than was expected, whereas those covered by Medicaid and those involved in injury-related lawsuits were less likely to return to work. It is hoped that this information can be used to design interventions aimed at improving this outcome of burn treatment.

Sporozoite transmission of three strains of Plasmodium knowlesi to Aotus and Saimiri monkeys

Attempts were made to infect Aotus and Saimiri monkeys with sporozoites of 3 strains of Plasmodium knowlesi to determine the potential of these animals in a monkey/malaria model. Splenectomized Saimiri and Aotus monkeys were infected with the H strain of P. knowlesi via sporozoites from Anopheles dirus mosquitoes. Prepatent periods ranged from 5 to 16 days. Saimiri monkeys infected with the Philippine strain had prepatent periods ranging from 6 to 8 days. Saimiri monkeys infected with the Hackeri strain had prepatent periods ranging from 6 to 11 days. Exoerythrocytic (EE) stages of the Philippine strain were readily demonstrated; EE stages of the H strain were less abundant. Results indicate that the Philippine strain of P. knowlesi in Saimiri monkeys has a course of parasitemia and EE stages similar to those previously seen in macaques and could serve as a reproducible model for biologic and immunologic studies.

Self-inflicted patient burns: suicide versus mutilation

Though suicide by burning is well-described, little information is available regarding patients who mutilate themselves by burning without suicidal intent. We reviewed 31 patients admitted from 1980 to 1991 with self-inflicted burns to describe differences between self-mutilation and attempted suicide (AS). In 16 patients who had mutilated themselves, mean burn size was 1.6% TBSA (range 0.3% to 9.0% TBSA) compared with 35.4% TBSA in the 15 patients who had attempted suicide (range 11.5% to 90% TBSA; p < 0.0001). Twelve of 15 patients who had attempted suicide used flammable liquids for self-immolation, whereas patients who had mutilated themselves often used techniques that they could control, including scalding, chemicals, and contact injuries. Most patients in both groups and previous histories of psychiatric disorders. Self-mutilators had a high incidence of personality disorders (56%), whereas the AS group more frequently suffered from depression (47%). Nine (56%) patients who had mutilated themselves had previous self-inflicted burns, compared with only one patient in the AS group. Mean lengths of stay, number of surgeries, and hospital and physician charges were higher for the AS group. Case examples of both types of injuries are presented. Burn care professionals should be familiar with syndrome of self-mutilation by burning. Patients often present with puzzling injuries and require psychiatric treatment in addition to burn care.

Rectal irrigations for the prevention of postoperative enterocolitis in Hirschsprung's disease

The purpose of this clinical trial was to examine the role of rectal irrigations in the prevention of postoperative enterocolitis in children with Hirschsprung's disease. Over the past 22 years 177 children had surgical treatment for Hirschsprung's disease at a single pediatric hospital. Five children have died of other causes. Of the remaining 172 patients, follow-up clinical information was obtained from 135 (78%). In 1989, all of the children undergoing surgical reconstruction for Hirschsprung's disease were placed on routine postoperative rectal irrigations with normal saline. The parents were instructed in the irrigation technique before leaving the hospital. Irrigations were started 1 to 2 weeks postoperatively and were performed two times a day for 3 months, then once a day for an additional 3 months. There were no complications from the irrigations themselves. A previous report from the authors' institution has documented five sudden deaths over the past 22 years from fulminant postoperative enterocolitis. These five children all had an unremarkable postoperative recovery, then developed a rapidly progressive diarrheal illness. All of these deaths occurred before the institution of routine postoperative irrigations. Of the 135 patients in this review, 40 had the postoperative rectal irrigations. The remaining 95 children serve as historical controls. Data analysis showed that 34 of the 95 children in the nonirrigation cohort developed postoperative enterocolitis compared with 3 of 40 in the rectal irrigation cohort; P < .001 using Fisher's exact test. In the authors' experience, routine postoperative rectal irrigations have significantly decreased the incidence and severity of enterocolitis in children after surgical correction of Hirschsprung's disease.

Gastrointestinal function after surgical correction of Hirschsprung's disease: long-term follow-up in 135 patients

This study is a retrospective review of all children treated for Hirschsprung's disease over the past 22 years at a single pediatric institution. During this time 177 patients had definitive surgical reconstruction. Five children died of causes unrelated to Hirschsprung's disease, and five children died from enterocolitis after an uneventful postoperative course. Clinical follow-up information was obtained from 135 (78%). Demographic data includes the following: sex ratio 74% male, 26% female; current mean age 9.9 years; mean length of follow-up 7.9 years (range, 3 months to 21.5 years). Mean age at surgical reconstruction was 1.6 years. Definitive surgical procedures included endorectal pull-through (Soave), 21%; modified Duhamel, 67%; extended side-to-side ileocolic anastomosis, 8%; rectal myomectomy, 4%. Transition zone was within rectum or rectosigmoid region in 86%. Overall, 32% (43/135) report difficulty with fecal soiling, and 12.6% (17/135) identify this as a severe problem. These numbers include patients with trisomy 21 and total colonic aganglionosis. Severe fecal soiling was reported in 7.1% (2/28) after an endorectal pull-through, and in 12.1% (11/91) after the modified Duhamel. The difference in incidence of soiling after these two procedures is not statistically significant. However, 40% (4/10) of the patients after the long side-to-side anastomosis for total colonic aganglionosis report severe problems with fecal soiling (P = .03). Surgical reconstruction for Hirschsprung's disease provides near-normal gastrointestinal function for the majority of children, but long-term follow-up shows significant residual problems with soiling in 12.6% of the patients. This is consistent with reported experience worldwide.

Predictors of mortality in pulmonary contusion

BACKGROUND

Associated injuries and central nervous system (CNS) trauma are historically associated with poor outcome in patients with pulmonary contusions, but the value of specific factors reflecting shock, fluid resuscitation requirement and pulmonary parenchymal injury in predicting mortality in this population is not well established.

METHODS

The medical records of 100 consecutive patients with pulmonary contusion, admitted over a 5-year period, were retrospectively reviewed. Survivors and nonsurvivors were compared in terms of age, Injury Severity Score (ISS), Glasgow Coma Score (GCS), PaO2/FiO2 (oxygenation ratio), the severity and adequacy of shock resuscitation reflected in plasma lactate, resuscitation volume and transfusion requirements, using one-way ANOVA. To determine the contribution of individual, interdependent variables to mortality, the data were then analyzed using multivariable analysis.

RESULTS

ISS and transfusion requirement were significantly higher, and GCS and PaO2/FiO2 at 24 and 48 hours after admission were significantly lower in nonsurvivors than in survivors. After multiple regression analysis, the factors most strongly associated with mortality included patient age, oxygenation ratio at 24 hours after admission, and resuscitation volume.

CONCLUSIONS

Outcome in patients with pulmonary contusion is dependent upon a number of variables including the severity of pulmonary parenchymal injury as reflected in PaO2/FiO2 ratio.

Anthropometric characteristics and performance related predictors of success in adolescent pole vaulters

The purpose of this study was to determine the anthropometric characteristics of skilled adolescent pole vaulters and to examine the strength of anthropometric and physical performance variables in predicting vaulting performance (N = 87; age group range 13-18 years). The vaulting height of the subjects ranged from 1.98 to 4.72m (mean 3.58 +/- s.d. 0.536m). The vaulters were classified as ectomorphic mesomorphs with an average somatotype of 1.6-4.2-3.5 (s.d. +/- 0.38-0.94-1.00). One way analysis of variance showed that while measures of stature, physical performance and vault performance significantly increased (p < 0.05) across age groups, somatotype and sum of skinfolds remained stable. Stepwise regression analysis showed the best predictor of vaulting performance was hand grip height (R2 = 0.78, p < 0.05). Correlation analysis showed that grip height was strongly correlated to vault height (r = 0.88), age (r = 0.72), body mass (r = 0.71), standing long jump (r = 0.69), running speed (r = 0.69), biceps girth (r = 0.66), standing height (0.65), calf girth (0.61) and pull-ups (r = 0.44). It was concluded that the somatotype of skilled young pole vaulters is similar to that of junior Olympic and adult Olympic vaulters, and that this somatotype is a selective factor for this event as early as thirteen years of age. Proficiency in pole vaulting is best predicted by grip height, which is strongly correlated to stature and simple field measures of leg speed and power, and upper body muscular endurance. These findings may be applied to the selection and training of young pole vaulters.

Peripherally inserted central venous catheters. Low-risk alternatives for ongoing venous access

We prospectively evaluated the use of peripherally inserted central venous catheters to provide ongoing venous access in general medical and surgical patients in a Department of Veterans Affairs medical center. Between 1985 and 1988 trained nurses successfully inserted 393 catheters in 460 suitable patients (an 85.4% success rate). Correct catheter tip placement in the superior vena cava was documented in 359 of the 393 (91.3%) catheter insertions, but an additional 30 catheters were in a position deemed adequate for the intended use. The mean duration of catheter use was 27.6 +/- 5.2 (1 standard deviation) days (median 20 days, range 1 to 370 days). A total of 65 patients left the hospital with catheters in place, with the mean length of catheter use at home being 36.2 +/- 6.0 days (range 2 to 266). In all, 79% of the catheters were in use until the successful completion of therapy or patient death; catheter-related complications led to premature catheter removal in the remaining 21%. Catheter-related complications included bland phlebitis (8.2%), occlusion (8.2%), local infection (3.6%), bacteremia or fungemia (2.1%), mechanical failure or rupture (2.6%), venous thrombosis (0.7%), and other (3.3%). One patient required vein excision for the management of suppurative phlebitis, but no deaths were attributed to catheter use. This study illustrates the use and safety of peripherally inserted central venous catheters to provide reliable vascular access over prolonged periods in an elderly veteran population. At our facility, percutaneous central venous catheters and surgically implanted (Hickman or Broviac) catheters are now reserved for use in patients in whom peripherally inserted catheters cannot be placed.

Multiple organ failure in patients with thermal injury

OBJECTIVE

To assess the frequency and significance of multiple organ failure in patients with burn injuries.

DESIGN

Retrospective review and prospective assessment of patients with acute burns.

SETTING

University hospital burn center.

PATIENTS AND METHODS

We reviewed 529 patients admitted for acute burn treatment whose lengths of stay exceeded 72 hrs. A new scoring system, the Thermal Injury Organ Failure Score, was used to assign scores from 0 (normal) to 6 (severe dysfunction) to each of 6 organ systems, which were then totaled to compile the overall score. This system was also used for prospective assessment of 83 adult burn patients, and compared with the Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system during the first week of treatment.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For 496 survivors, mean organ failure score was 3.28, compared with 23.1 in 33 nonsurvivors (p < .0001). All nonsurvivors but one had scores of > or = 15, indicating dysfunction of at least three organs. Scores and mortality rate increased with age and burn size. Pulmonary dysfunction was the most frequent form of organ failure seen, but correlated less with outcome than did cardiovascular or neurologic scores. Sepsis was present in 22 of 33 patients who died. In the prospective study, organ failure scores correlated with outcome more closely than did APACHE II scores. Weekly evaluation of these patients demonstrated progressive divergence in scores between survivors and nonsurvivors.

CONCLUSIONS

Multiple organ failure was almost invariably present in burn patients who died > 72 hrs after injury. Burn victims, who have been excluded from reviews of multiple organ failure, appear to manifest organ failure in a manner similar to that of other surgical populations. The scoring system reported here may prove useful in evaluating organ failure in thermally injured patients.

Trypanosomes and microfilariae in feral owl and squirrel monkeys maintained in research colonies

A group of 358 owl and squirrel monkeys imported from Colombia, Peru, and Bolivia for the U.S. Agency for International Development Malaria Vaccine Development Program was examined for trypanosomes and microfilariae. Trypanosoma rangeli, isolated by hemoculture from Aotus nancymai, Saimiri b. boliviensis, and S. b. peruviensis, accounted for 76.6% of all trypanosome infections. Trypanosoma cruzi was isolated from 25 of 194 S. b. boliviensis, including two mixed infections with T. rangeli. Identifications of trypanosomes were confirmed by blinded tests with a panel of five rRNA probes on a subsample of cultures identified morphologically. Although no trypanosomes were isolated from Aotus vociferans or A. lemurinus griseimembra, positive serologic responses to T. cruzi were observed by indirect immunofluorescence assay in all species of monkeys examined and ranged from 42.1% among S. b. peruviensis to 92.3% among A. vociferans. Among T. rangeli-infected monkeys, 43.7% were seronegative for T. cruzi. No microfilariae were found in S. b. boliviensis or A. l. griseimembra. Mansonella barbascalensis and Dipetalonema caudispina were observed in A. vociferans, M. panamensis in A. nancymai, and M. saimiri and D. caudispina in S. b. peruviensis. Such naturally occurring infections in imported animal models are potential sources of accidental transmission to animal handlers and uninfected laboratory animals and can introduce confounding variables into otherwise well-planned and well-executed studies.

Increasing the wearing time of vinyl urinary drainage bags by decontamination with bleach

The purpose of this study was to determine the safety of 4 week re-use of vinyl urinary leg and bed bags in the acute rehabilitation setting when decontaminated daily with a dilute bleach (sodium hypochlorite) rinse. Patients requiring urinary bags (n = 54) were randomly assigned to Control (C) and Experimental (E) groups. C's bags were replaced weekly; E's only after four weeks. Both groups received identical daily bag decontamination and weekly urine and bag cultures. No significant differences were found between groups with ANCOVA, controlling for baseline urine cultures, age, number of days catheterized, and use of antibiotics. Thirty different organisms were cultured in urine and bags; when the procedure was done daily, all bag cultures showed only minimal contamination (0-100CFU/mL). Bacterial growth (4.4% of leg bags) > 100CFU/mL was found only when the daily decontamination procedure had been omitted. In fact, 57% of leg bags and 76.5% of bed bags returned with no growth. We conclude that it is safe and cost effective to reuse vinyl urinary leg and bed bags for four weeks.

Differentiation of trypanosomatid species by hybridization to selected rRNA probes

Oligonucleotides with sequences complementary to selected regions of the Trypanosoma cruzi large sub-unit ribosomal RNA (rRNA) were used to specifically detect and quantify T. cruzi and other kinetoplastids. By selecting sequences with varying homologies with Crithida fasciculata, another kinetoplastid for which this sequence was known, probes which hybridized to T. cruzi alone or T. cruzi and T. rangeli, various Leishmania species or C. fasciculata were identified. This identification was possible even though the sequences of the large sub-unit (LSU) rRNA of T. rangeli and Leishmania are not known. None of the probes hybridized with rRNA from mouse or human cell lines, and all could quantitatively detect T. cruzi in tissue culture cells. Probing of replicate membranes with these different oligonucleotides allowed discrimination between these species. The functional application of rRNA-specific probes in diagnosis was demonstrated by identification of unknown trypanosomatids in hemocultures of wild-captured owl and squirrel monkeys using a combination of oligonucleotides. Therefore, these probes should be useful in diagnosis and identification of T. cruzi and related parasites.

Susceptibility of four species of copepods, from areas of endemic Dracunculus medinensis, to the North American D. insignis

Studies of the relative importance of different copepod species in areas of endemic dracunculiasis have been restricted, in part, by limited access to Dracunculus medinensis. However, development of the D. insignis-ferret model provides a source of larvae of a species closely related to D. medinensis. Using larvae derived from this model, the susceptibility of four species of copepods from D. medinensis-endemic areas was compared to that of Canadian Acanthocyclops vernalis, which is fully susceptible to D. insignis. Cryptocyclops linjanticus, from Cameroon, was susceptible but highly sensitive to infection, resulting in high mortality. Mesocyclops aequatorialis similis, also from Cameroon, was fully susceptible, but M. leuckarti leuckarti from Pakistan was partially refractory to D. insignis, as was Thermocyclops emini from Cameroon. Comparisons of infection rates and mean and maximum larval recoveries at three to four and 16-20 days after infection indicated that exposure to 15 first-stage larvae exceeded the threshold of tolerance of A. vernalis, C. linjanticus and M. a. similis to infection with D. insignis. This may account for a decreased survival rate in these copepods which is not evident in the partially refractory T. emini and M. l. leuckarti. The patterns of susceptibility of these copepods to D. insignis are the same as those of copepods exposed to D. medinensis, and indicate that D. insignis can be used to examine factors influencing the susceptibility of copepods to dracunculid infection.

Bacterial translocation is prolonged in burned mice infected with cytomegalovirus

Cytomegalovirus is seen frequently in patients with burns and may enhance morbidity and mortality rates. Burned BALB/c mice that were given murine cytomegalovirus by intraperitoneal injection demonstrate increased bacterial translocation, as evidenced by positive mesenteric lymph node culture at 5 days after burn injury. The present experiment was conducted to investigate the time course and mechanism of this effect. A significant delay in the resolution of positive mesenteric lymph node cultures was observed with thermal injury alone. This was further reduced by the addition of murine cytomegalovirus infection to thermal injury. No such delay was seen with murine cytomegalovirus infection alone or in controls.

Effect of caffeine ingestion on alveolar ventilation during moderate exercise

The purpose of this study was to examine the effect of caffeine ingestion on alveolar ventilation and physiological dead space ventilation during exercise in high and low caffeine users. Eleven males (mean age 26.4 +/- 5.4 years), classified as either high caffeine users (greater than 350 mg/d, n = 6) or low caffeine users (less than 50 mg/d, n = 5) performed two treadmill exercise conditions at a constant work rate (50% VO2max) 45 min after ingestion of 3.3 mg of caffeine/kg body weight or placebo using a double-blind protocol. Open circuit spirometry was used to determine ventilatory and gas exchange variables every 10 min during the 50 min of walking exercise. Analysis of variance showed that caffeine produced significant differences in alveolar ventilation (VA) and the physiological dead space ventilation/tidal volume ratio (VD/VT) with VA increased from 1.36 to 1.54 L/breath and VD/VT decreased from 22.3 to 20.5% between the placebo and caffeine treatments, respectively. Additionally, caffeine ingestion produced a significant increase in tidal volume (VT) and a significant decrease in frequency of breathing (fb). We conclude that caffeine consumed prior to exercise enhances ventilatory dynamics during exercise without regard to prior habitual caffeine consumption.

Use of pooled formalin-preserved fecal specimens to detect Giardia lamblia

Three formalin-preserved fecal specimens from the same child attending a child-care center were pooled and compared with the three separate individual specimens by a single microscopic examination of concentration sediment for Giardia lamblia. The sensitivity of the pooled system was 100% when two or more individual specimens were positive and 88% when only one individual specimen was positive. The organism density in a single specimen was not a factor of whether the pool of specimens was positive or negative. Nearly half of the pools that contained positive specimens had only one of three specimens with positive results, reinforcing the need for multiple stool examinations when diagnosing G. lamblia infections.

Differences in mortality from thermal injury between pediatric and adult patients

Children differ from adults in their responses to thermal injury, as reflected by higher reported mortality rates for equivalent major injuries. The age at which children's survival rates equal those of young adults has not been well defined, and some investigators have recently claimed that pediatric and adult burn mortality do not differ. We evaluated age-related mortality among 1,443 consecutive patients without inhalation injury treated from 1978 to 1988, inclusively. The sample consisted of 595 children aged 12 years or less, 243 children aged 13 to 20 years, and 605 young adults aged 21 to 40 years who served as a comparison group of patients with the best predicted survival. We separately examined mortality in patients with burns exceeding 30% total body surface area. There were no significant differences in mortality between age groups for the study sample as a whole, but among patients with large burns, children aged 0 to 48 months had higher mortality than comparably injured adults (31% v 12%, P less than .05 by analysis of covariance). Improvements in survival were also demonstrated between the first and second halves of the study period for children aged 25 months to 8 years. These data indicate that children 48 months of age and younger do not tolerate large thermal injuries as well as adults. Improvements in pediatric burn survival are being achieved in most age groups.

Threshold of detection of Cryptosporidium oocysts in human stool specimens: evidence for low sensitivity of current diagnostic methods

To determine the minimum number of Cryptosporidium oocysts that can be detected in stool specimens by diagnostic procedures, stool samples seeded with known numbers of Cryptosporidium parvum oocysts were processed by the modified Formalin-ethyl acetate (FEA) stool concentration method. FEA concentrates were subsequently examined by both the modified cold Kinyoun acid-fast (AF) staining and fluorescein-tagged monoclonal antibody (immunofluorescence [IF]) techniques. Oocysts were more easily detected in watery diarrheal stool specimens than they were in formed stool specimens. For watery stool specimens, a 100% detection rate was accomplished at a concentration of 10,000 oocysts per g of stool by both the AF staining and IF techniques. In formed stool specimens, 100% of specimens seeded with 50,000 oocysts per gram of stool were detected by the IF technique, whereas 500,000 oocysts per g of stool were needed for a 100% detection rate by AF staining. Counting of all oocysts on IF slides indicated a mean oocyst loss ranging from 51.2 to 99.6%, depending on the stool consistency as determined by the FEA concentration procedure. Our findings suggest that the most commonly used coprodiagnostic techniques may fail to detect cryptosporidiosis in many immunocompromised and immunocompetent individuals.

Dietary omega-3 fatty acids decrease mortality and Kupffer cell prostaglandin E2 production in a rat model of chronic sepsis

We tested the hypothesis that substitution of omega-3 fat for dietary omega-6 fat would reduce mortality and decrease Kupffer cell prostaglandin E2 (PGE2) production in a rat model of chronic sepsis. Rats were fed via gastrostomy for 12 days with isonitrogenous, isocaloric diets containing 15% of calories as either safflower oil (omega-6) or a 10:1 mixture of menhaden oil (omega-3) and safflower oil. After five days of feeding, animals received an intra-abdominal abscess of defined bacterial content. Survivors were killed on post-laparotomy day 6 in conjunction with liver perfusion and protease liver digestion for Kupffer cell isolation. Kupffer cell PGE2 production was measured by radioimmunoassay after 18 hours of cell culture and again after stimulation with 0 LPS, 10 ng/ml LPS, and 10 micrograms/LPS. Mortality was decreased in menhaden oil-fed animals compared with safflower oil-fed animals (16% vs. 35%). Kupffer cell PGE2 production was decreased in menhaden oil-fed animals at 18 hours (354 +/- 54 vs. 570 +/- 95 pg/0.1 ml; p = 0.09) and after stimulation with 10 micrograms/ml LPS (140 +/- 41 vs. 288 +/- 45 pg/0.1 ml; p = 0.03) compared with safflower oil-fed animals.

Isoenzyme profiles of four strains of Giardia lamblia and their infectivity to jirds

The infectivity to jirds (Meriones unguiculatus) and the cyst excretion pattern of a recently isolated strain of Giardia lamblia from Egypt, Strain CDC:1088:1 (EGY), were compared to those of three well-established strains. All five jirds inoculated orally with strain UNO:0487:1 (UNO) became infected and began excreting cysts 3-6 days post-infection (dpi); no cysts were detected between 8-12 dpi after which time cysts were produced through day 19. Four of the five jirds infected with Strain ATCC:30957 (WB) and three of the five jirds infected with strain CDC:0284:1 (VA) excreted cysts from 6-20 dpi and 6-22 dpi, respectively. One of five jirds inoculated with EGY excreted cysts on 8 dpi only. At necropsy, trophozoites were recovered from only three UNO-infected jirds but from all WB- and VA-infected jirds that excreted cysts. The one jird which excreted cysts of EGY was negative at necropsy, but EGY trophozoites were found in one non-patient jird. Isoelectric focusing indicated that these four strains of G. lamblia represented three zymodemes. WB and VA were assigned to one zymodeme, EGY to a second, and UNO, which shared common bands with both other zymodemes, to the third. Although the similarities and differences in infectivity and cyst excretion patterns appear to coincide with the zymodemes to which the strains can be assigned, further study is needed to examine the parasitologic behavior of these strains in relation to isoenzyme patterns.