Trifluoroethanol-assisted protein folding: fragment 53--103 of bovine alpha-lactalbumin

Fragment 53--103 of bovine alpha-lactalbumin, prepared by limited peptic digestion of the protein at low pH, is a 51-residue polypeptide chain crosslinked by two disulfide bonds encompassing helix C (residues 86--98) of the native protein. Refolding of the fully reduced fragment (four--SH groups) is expected to lead to three fully oxidized isomers, the native (61--77, 73--91) and the two misfolded species named ribbon (61--91, 73--77) and beads (61--73, 77--91) isomers. The fragment with correct disulfide bonds was formed in approx. 30% yield when refolding was conducted in aqueous solution at neutral pH in the presence of the redox system constituted by reduced and oxidized glutathione. On the other hand, when the reaction was conducted in 30% (v/v) trifluoroethanol (TFE), the oxidative refolding to the native isomer was almost quantitative. To provide an explanation of the beneficial effect of TFE in promoting the correct oxidative folding, the conformational features of the various fragment species were analyzed by far-UV circular dichroism measurements. The fully reduced fragment is largely unfolded in water, but it becomes helical in aqueous TFE. Correctly refolded fragment is produced most when the helical contents of the reduced and oxidized fragment in aqueous TFE are roughly equal. It is proposed that 30% TFE promotes a native-like format of the fragment and thus an efficient and correct pairing of disulfides. Higher concentrations of TFE, instead, promote some non-native helical secondary structure in the fragment species, thus hampering correct folding.

Endoscopic palliation of esophageal and cardial cancer: neodymium-yttrium aluminum garnet laser therapy

The aim of this study was to evaluate the impact of laser palliation on symptoms such as dysphagia and bleeding in patients with esophageal and cardial carcinomas. From November 1992 to October 1997, 174 patients with unresectable esophageal and cardial carcinomas were treated with neodymium-yttrium aluminum garnet laser therapy. The indications for palliative treatment were advanced tumor in 96 patients and high surgical risk in 78. The tumor involved the esophagus and cardia in 107 and 67 patients respectively. The mean length of the tumors was 6 cm. Two laser sessions (range 1-4) were necessary for recanalization. During the follow-up, the average interval between the laser sessions was 2 months. Overall, no early and late complications or hospital mortality occurred. The quality of palliation was excellent or good in 82%, of the patients. The mean survival time was 6 months, and mortality was not related to the procedure. Endoscopic laser therapy in patients with vegetant or hemorrhagic carcinomas may represent the best therapy, with acceptable morbidity and mortality rates and satisfactory functional results.

[Palliative treatment of esophageal and cardial carcinoma]

Recent series reported increasing incidence of esophageal and cardial cancers with prognosis still severe in spite of surgical progress. The late diagnosis reduces the chance of radical surgery; on the other hand about 80-90% of patients develop local or distant recurrence. Therefore the treatment of esophageal and cardial cancer is often palliative: surgical resection is reserved only to selected cases. Endoscopic palliation was the treatment of choice in a total of 265 patients 174 of which received laser therapy and 91 prosthesis intubation. The results it good in about 80% of cases.

[Perforation of the colon by a foreign body]

Perforation of the colon carries a high mortality and morbidity. Perforations caused by foreign bodies are relatively rare and appear to be less often associated with postoperative complications than perforations due to organ disease. Depending upon the extent of the perforation and its anatomical site, as well as on the basis of the presence of diffuse or circumscribed peritonitis, the treatment of foreign-body perforation will vary from simple suturing, with or without a protective colostomy, to exteriorization in the form of a colostomy, and the Hartmann operation.

[The hypothesis of a diagnostic-prognostic assessment of intestinal invagination with the aim of treatment by echo-guided pneumatic reduction]

The authors investigated the role of US in the diagnostic-prognostic evaluation of enteric intussusception, for the use of US-guided pneumatic reduction (RPEG). In the last 5 years, 59 young patients were examined; 44 of them had clinically suspected enteric intussusception which was confirmed by US. US allowed site and nature of the condition to be demonstrated (sensitivity and specificity: 100%), while supplying helpful predictive prognostic elements as to the extent of intussuscepted loop involvement (predictive prognostic value: 100%). On the contrary, its etiological screening capabilities were poor (11%) in the identification of secondary forms (5 ileal diverticula). A grading score was introduced to select the patients undergoing RPEG. Six clinical and US parameters were considered, with values increasing according to severity of the condition. The higher the score, the lower the chances of therapeutical success with RPEG. In 3 cases (2 loop necroses and 1 severe intestinal obstruction) with US score greater than 6 [9] and clinical score greater than 11 [15], RPEG, was replaced by surgery. Fourteen patients underwent RPEG: positive results were obtained in 12 cases (85%). In one case, a short-term relapse (within 6 hours) was observed.

[The intraoperative echography of malignant hepatic lesions]

IOU (intraoperative ultrasound) is nowadays an indispensable technique for the surgeon to confirm the information collected from preoperative tests or to gain further information that may modify surgical strategy. A series of 350 patients were studied with IOU: in 67 cases the liver was involved, with 23 malignant lesions. In the latter group, 10 lesions were found which had been missed even at palpation; the size of 9 of them could be correctly assessed, which had been overestimated in 8 cases and underestimated in 1 before surgery. Moreover, in 39.1% of the cases, the information yielded by IOU determined a change in surgical strategy, favoring a more accurate dissection of the lesion. Surgery was modified depending on the recognition of: nonpalpable lesions (5 cases); portal thrombosis (1 case); lesions bigger (2 cases)--smaller (2 cases) than preoperatively diagnosed. Moreover, IOU was a useful tool to guide the surgeon during intervention, by yielding accurate anatomical information on the segment/segments hosting the lesion.

[The echo-guided fine-needle biopsy of thoracic and abdominal masses]

Five hundred and seventy-two US-guided fine-needle biopsies were performed on 561 patients (1.2 puncture/patient); in two cases only minor complications were observed. The patients were 12 to 86 years old--most of them ranging 40 to 75. In 5.42% of cases FNAB proved inadequate; 1.75% of the diagnoses was questionable, 28.89% was negative, and 63.98% positive. A comparison with histology was possible in 218 cases: 2 false positives and 5 false negatives were observed. The low rate of false-positive findings demonstrates US-guided FNAB to have high positive predictive value. The method had 95% sensitivity, 98.4% specificity and 84.3% accuracy. The high reliability of FNAB depends on the possibility of centering the lesion through the direct US visualization of the needle tip. This characteristic, together with the presence of the cytologist, who immediately evaluates the aspirated material, helps reduce the number of unnecessary biopsies and, consequently, complications.

[Ultrasonography of the borderline between normal and pathological state of the hip in newborn infants (borderline hip)]

Infant hips are classified, according to Graf, in 4 US types on the basis of the morphologic changes in both the cartilaginous and the bony roofs (type I, II, III, IV). Out of 6,000 examined hips, 170 (2.8%) were considered, which could be classified neither as type I (mature) nor as type II (delayed/immature ossification). These hips were called borderline hips. They exhibited some characteristic US features: good bone modeling, rounded cotyle, and alpha angle 60 degrees +/- 2. They were always observed during the first month of the patients' life. Anamnestic data were not specific (27.5% breech delivery, and 13% oligohydramnios); clinics sometimes overestimated the actual anatomic development (64/170 cases with positivity of Ortolani's sign and/or restricted abduction; 25% of patients presented with no suspicious signs). Dynamic hip examination showed only physiological cranial deflection of the cartilaginous roof. Finally, borderline hips developed into type I hips in 99% of cases, within the third month of the patients' life.

[Diagnostic errors in the echography of the hip in newborns]

Neonatal hip sonography according to Graf employs a standardized image in a frontal section plane ("3-point system") and a good scanner adjustment (the femoral head must be anechoic, like the hyaline cartilage roof triangle). Pathologic conditions can change some of these parameters. The authors examined 6,000 neonatal hips in order to point out the commonest causes of diagnostic error. Two types of error were considered: method errors and interpretation errors. Method errors: they are due to the choice of transducer and frequency, to scanner adjustment and definition of the standard section plane. Their incidence was 2.25% and supported by an uncorrect definition of the standard section plane. Interpretation errors: they come from the wrong localization of some reference points--i.e., lower iliac margin, labrum--, uncorrect evaluation of increased echogenicity of the cartilaginous roof, infant age, application of radiographic criteria and uncorrect measurements of alpha and beta angles. Interpretation errors had 5.5% incidence; they were all due to the uncorrect measurement of alpha (3.18%) and beta (2.33%) angles, especially in pathological hips (68%). To reduce the number of errors, the authors suggest to strictly apply Graf's method, to make a diagnosis based on the morphological changes of the cartilaginous and osseous acetabular roof and, only later on, to measure alpha and beta angles to confirm the diagnosis or in the follow-up.

[Endometriosis on a cesarean cicatrix. Apropos of 3 cases]

Endometriosis on a caesarean scar is a well-known, though not frequent event. The lesion generally presents as a painful nodule of the abdominal wall during the menstrual cycle. Pain cyclicity is a useful sign for diagnosis. Treatment consists of removal. Three cases are reported.

[Echography in the diagnosis of spontaneous hematoma of the rectus muscle]

After a brief explanation of the pathogenesis and of the clinical picture of spontaneous rectus muscle hematoma, the Authors describe 9 diagnosed cases by ultrasonography. The various echographic appearances of this disease are described and the importance of ultrasonography for a correct diagnosis and to avoid unnecessary laparotomy is emphasized.