Vaccines against enterotoxigenic bacterial pathogens based on hybrid Salmonella that express heterologous antigens

In this report, we examine two aspects in the development of a vaccine against enterotoxigenic bacterial pathogens based on hybrid Salmonella that express heterologous antigens. First, we describe the construction of a non-toxic fusion peptide for immunization against Escherichia coli that produce heat-labile (LT) and heat-stable (ST) enterotoxins. For that construction, the 5' terminus of the gene coding for ST was fused to the 3' terminus of the gene coding for the binding subunit of LT(LT-B). The ST gene was constructed synthetically with appropriate restriction sites to permit in-frame, downstream insertion. Maximum expression of ST antigenicity was obtained when a seven-amino-acid proline-containing linker was included between the LT-B and ST moieties. The purified LT-B/ST fusion peptide consisted of a single polypeptide chain with an apparent molecular weight of 18,000. The LT-B/ST fusion peptide was non-toxic and immunologic determinants of both LT and ST were recognized by antibodies directed against the native toxins. Animals immunized with either crude or purified preparations containing the hybrid molecule produced antibodies that were able to recognize native toxin in vitro. Significantly, these antibodies were able to neutralize the biological activity of native ST. The second aspect reported here examines a mechanism for stabilizing expression of heterologous antigens in attenuated Salmonella mutants by integration of the heterologous gene (LT-B) into the chromosome of the carrier. A comparative in vitro study of the levels of expression of LT-B between the cointegrate strain and an isogenic strain carrying the LT-B gene on a multicopy plasmid demonstrated that the initial levels of expression of both strains is similar, that the plasmid-carrying strain loses the ability to express the heterologous antigen very quickly and that the cointegrate continues to maintain and express the antigen without the requirement for a stabilizing antibiotic.     

Construction of a nontoxic fusion peptide for immunization against Escherichia coli strains that produce heat-labile and heat-stable enterotoxins.

The 5' terminus of the gene that codes for the heat-stable enterotoxin of Escherichia coli (ST) was genetically fused to the 3' terminus of the gene that codes for the binding subunit of the heat-labile enterotoxin of E. coli (LT-B). The ST-encoding gene used for these studies was constructed synthetically with appropriate restriction sites to permit in-frame, downstream insertion of the oligomer. For this construction, maximum expression of ST antigenicity was obtained when a seven-amino-acid, proline-containing linker was included between the LT-B and ST moieties. The LT-B-ST fusion peptide was purified by affinity chromatography and consisted of a single polypeptide chain with an apparent molecular weight of 18,000 when examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. There was no evidence of multimer formation and no change in the mobility of the fusion peptide when it was boiled in SDS or in SDS with dithiothreitol. The LT-B-ST fusion peptide was nontoxic, and immunologic determinants of both LT and ST were recognized by antibodies to the native toxins. More importantly, the LT-B-ST fusion peptide was immunogenic. Animals immunized with crude or purified preparations containing the hybrid molecule produced antibodies that were able to recognize native toxin in vitro. Significantly, these antibodies were able to neutralize the biological activity of native ST.     

Left ventricular systolic response to exercise in patients with systemic hypertension without left ventricular hypertrophy

Supine exercise radionuclide angiography was performed in 367 men to assess left ventricular (LV) systolic response to exercise; 58 had systemic hypertension without LV hypertrophy on a resting electrocardiogram and 309 were normotensive. All patients met the following criteria defining a low pretest likelihood of coronary artery disease: age less than 50 years; normal electrocardiographic response to exercise; absence of typical or atypical chest pain; and exercise heart rate greater than 120 beats/min. Patients taking beta-receptor blockers were excluded. There were no significant differences between hypertensive and normotensive groups in peak exercise heart rate, workload or exercise duration. However, hypertensive patients had significantly higher peak exercise systolic blood pressures and peak exercise rate-pressure products. There were no differences between patients with and without hypertension in resting ejection fraction, peak exercise ejection fraction (hypertensive patients 0.71 +/- 0.01, normotensive patients 0.70 +/- 0.05) or change in ejection fraction at peak exercise (hypertensive patients 0.07 +/- 0.01, normotensive patients 0.07 +/- 0.04). Diastolic and systolic ventricular volumes tended to be smaller in the hypertensive patients, but the difference was not statistically significant. The change in systolic volume with exercise was similar in the 2 groups (hypertensive -10 +/- 3 ml/m2, normotensive -10 +/- 1 ml/m2). In the absence of electrocardiographic evidence of LV hypertrophy, systemic hypertension does not influence LV systolic response to exercise.     

Direct determination of surface tension in the lung.

We have used the spreading behavior of small drops of several fluorocarbon fluids and silicone oil on air-liquid interfaces to measure the surface tension of lungs in situ. The test fluids were calibrated in a surface balance at 37 degrees on monolayers of dipalmitoylphosphatidylcholine. At particular surface tensions characteristic of each fluid used, an increase in the tension of 1 mN/m or less caused the droplets to spread reversibly from a sphere to a lens shape. Using micropipettes we placed such droplets on the alveolar surfaces of excised rat lungs held at functional residual capacity and 37 degrees and found that the surface tension remained below 9 mN/m for at least 30 min. The surface tension-volume relationship was linear for tensions ranging from 9 to 20 mN/m.     

Splenic Artery Embolization after Delayed Splenic Rupture Following Blunt Trauma: Is Nonoperative Management Still an Option in This Cohort?

Patients treated with splenic artery embolization (SAE) >48 hours after a blunt injury for a delayed splenic rupture (DSR) were assessed for the need for a subsequent splenectomy. Thirty-four patients underwent SAE for DSR over 10 years at our level 1 trauma center, performed at a median of 4.5 days after the injury (interquartile range = 5.5), and the patients were followed up for a median of 11 months (interquartile range = 31). There were 3 occurrences of rebleeds, and 2 patients required splenectomy (5.9%). This study showed that treatment with SAE after DSR results in splenic salvage in 94.1% of patients.     

Gastrointestinal symptoms are more intense in morbidly obese patients

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass is an effective treatment for morbid obesity. However, little information is available on gastrointestinal (GI) symptomatology in this population. This study compares GI symptoms in morbidly obese patients to that of control subjects. METHODS: A previously validated, 19-point GI symptom questionnaire was administered prospectively to each patient seen for surgical consultation for morbid obesity. The symptoms were then grouped into 6 clusters as follows: (1) abdominal pain, (2) irritable bowel, (3) GERD, (4) reflux, (5) sleep disturbance, (6) dysphagia. The result of each cluster of symptoms expressed as mean +/- standard deviation of obese versus control is compared using student's t-test with significance p = 0.05. RESULTS: Forty-three patients (40 female, 3 male) age 37.3 +/- 8.6 with BMI 47.8 +/- 4.9, and 36 healthy control subjects (23 female, 13 male), age 39.8 +/- 11.2, completed the questionnaire. Results of each cluster for morbid obese vs control subjects are expressed as mean +/- standard deviation: Abdominal pain 25.3 +/- 18.0 vs 12.1 +/- 11.4, p = 0.0002; irritable bowel 23.0 +/- 14.8 vs 15.6 +/- 13.3, p = 0.02; GERD 40.3 +/- 18.9 vs 22.3 +/- 16.1, p = 0.0001; reflux 29.9 +/- 19.0 vs 11.8 +/- 13.4, p = 0.0001; sleep disturbance 50.6 +/- 28.9 vs 32.9 +/- 26.8, p = 0.006; dysphagia 10.9 +/- 15.6 vs 7.2 +/- 10.6, p = NS. CONCLUSIONS: Morbidly obese patients experience more intense GI symptoms than normal subjects, whereas dysphagia is equivalent to normal subjects. These data may be important in counseling patients and understanding that their complaints are legitimate. Follow-up in the postoperative period is needed to determine if these symptoms are improved with an operation.     

Protective efficacy of low-dose amantadine in adults challenged with wild-type influenza A virus.

The prophylactic efficacy of a low dose (100 mg) of amantadine hydrochloride against experimental challenge with influenza A/Texas/1/85 (H1N1) wild-type virus was determined in healthy adult volunteers in a placebo-controlled, double-blind, randomized trial. No side effects of the 100-mg dose were observed in the amantadine-treated volunteers. Compared with placebo, 100 mg of amantadine significantly reduced the frequency of illness (9 of 22 versus 2 of 22 volunteers, P less than 0.04) and provided 78% protection against influenza illness. The two ill volunteers in the amantadine group had rhinitis only, whereas most of the ill placebo controls developed both systemic and upper-respiratory-tract illness. Wild-type virus was recovered from 50% of the amantadine-treated volunteers, compared with 82% of the placebo controls. Of note, the infected amantadine recipients shed 100 times less virus and shed virus for half as many days as did the infected placebo recipients. Although amantadine restricted viral replication, it did not interfere with the development of an antibody response to influenza virus. These results indicate that in adults experimentally challenged with influenza wild-type virus, 100 mg of amantadine is effective both in the prevention of influenza illness and in the restriction of virus replication.     

Iotrol versus metrizamide in lumbar myelography: a double-blind study

In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.