Hemocompatibility of stent materials: alterations in electrical parameters of erythrocyte membranes.

BACKGROUND: It is presently unknown if stents used in the correction of artery stenosis are fully hemocompatible or if their implantation causes alterations at the level of the plasma membrane in red blood cells. METHODS: We addressed this important issue by measuring the passive electrical properties of the erythrocyte membrane before and after stent insertion by means of dielectric relaxation spectroscopy in the radiowave frequency range in a series of patients who were undergoing standard surgical treatment of arterial disease. RESULTS: Our findings provide evidence that full hemocompatibility of stents has not yet been reached, and that there are some measurable alterations in the passive electrical behavior of the red blood cell membrane induced by the presence of the stent. CONCLUSION: It is possible that these changes do not have any physiological significance and simply reflect the intrinsic variability of biological samples. However, caution is urged, and the technique we describe here should be considered when investigating the hemocompatibility of a medical device at a cell membrane level.

Structural alteration of erythrocyte cell membrane in presence of artificial prostheses: a radiowave dielectric spectroscopy study.

The exposure of a biomaterial to blood gives rise to complex reactions playing an important role in many biological phenomena, such as the problem of biocompatibility and the mechanism of cardiovascular and thromboembolic diseases. In the present work, we use a frequency-domain dielectric spectroscopy approach to evaluate possible changes in the passive electrical parameters of the erythrocyte membrane, i.e., the membrane conductivity sigma(s) and the membrane permittivity epsilon(s), after the insertion of a prosthesis (mean implantation time 8 days) in the circulatory system of patients treated for aortic aneurysm and the consequent interactions of erythrocyte cells with the biomaterial surface. We observe an increase of both the membrane conductivity and membrane permittivity, indicating changes at molecular level in the structural organization of the membrane. These membrane alterations can be viewed as precursory events for the initiation of the complex sequence of enzymatic reactions that take place on the material surface. Our results, although preliminary imply that a direct interaction between erythrocyte cell membrane and vascular prostheses may occur, causing a marked alteration in the electrical properties of the cell membrane. These findings might have relevant clinical implications and might offer possibilities to predict biocompatibility of biomaterials and give some further suggestions to resolve the problem of biomaterial-associated thrombogenicity.

Cost-effectiveness study of imipenem/cilastatin versus meropenem in intra-abdominal infections.

BACKGROUND: The efficacy of two carbapenems, imipenem/cilastatin (I/C, 1.5 g daily) versus meropenem (3 g daily) in intra-abdominal infections was assessed in a recent multicenter randomized clinical trial. The aim of this article is to perform a cost-effectiveness analysis as in real-world practice according to the findings of this clinical trial. METHODS: A decision tree was used to estimate the clinical outcomes and direct costs of treating intra-abdominal infections using the two carbapenems from the perspective of the Italian National Health Service (INHS) or a private insurance company (PIC). RESULTS: In a population of 30,000 patients with intra-abdominal infections in Italy, it was estimated that 97 potential deaths/year could be avoided if these patients were treated with I/C versus meropenem. In addition, from the perspective of INHS, the total costs of treatment were estimated as ITL 106,874 million and 134,042 million for I/C and meropenem, respectively. In favor of the PIC point of view, the total costs were estimated as ITL 110,500 million and 135,899 million for I/C and meropenem, respectively. CONCLUSION: The treatment of intra-abdominal infections with I/C is shown to be more effective (97 deaths avoided/year) and less costly than with meropenem (with a saving of ITL 27,168 and 25,399 million/year for INHS and PIC, respectively).

[The role of surgery in the treatment of appendicular abscesses]. / Il ruolo della chirurgia nel trattamento degli ascessi appendicolari.

The management of appendiceal abscesses is still discussed and many different approaches are nowadays adopted. The aim of this study was to analyze retrospectively our experience with this disease to value the results of drainage of the abscess and appendectomy in one stage in presence of appendiceal abscesses. We studied 44 patients consecutively observed in our Department of General Surgery all submitted to drainage of the abscess and appendectomy for acute appendicitis with periappendiceal abscess. Preoperative ultrasonography showed an accuracy of 85.7% in detecting the presence of an abscess. Mean size of the abscesses were 5 cm (from a minimum of 3 cm to a maximum of 9 cm). The mean duration of surgical operation was 48 minutes (min 35'-max 95'), with a mean in-hospital stay of 6.2 days. Morbidity rate was 9% and was due in 75% of cases to wound infection and in 25% of cases to wound dehiscence. Neither major morbidity nor mortality were observed. In consideration of the results the authors conclude that even in presence of an appendiceal abscess, appendectomy with abscess drainage is not only a safe operation with a low morbidity rate but the procedure of choice allowing a significative reduction of hospitalization and health cost.

[Fistulectomy with closure by first intention in the treatment of perianal fistulae]. / La fistulectomia con chiusura per prima intenzione nel trattamento delle fistole perianali.

The authors report in a retrospective study their experience in the treatment of anal fistulas suggesting the total exercises of the fistula with primary closure of external and internal anal sphincters and rectal mucosa. In our department of surgery between 1987 and 1993, 36 patients (22 males and 14 females) with anal fistulas (17 intersphincteric, 15 trans-sphincteric and suprasphincteric) were treated with this technique. Postoperative in-hospital stay ranged between 2 and 5 days (mean 3.1) and surgical healing needed 12-15 days. A dehiscence of distal tract was observed in 3 cases (8.2%). in these cases secondary closure of the wound needed 24-28 days. All the patients controlled at follow-up (it lasted at least 1 year) did not show rectal incontinence for gas or stools. The authors conclude that total exeresis with primary closure is a safe procedure indicated in the treatment of anal fistula not associated to inflammatory bowel disease in consideration of earlier healing and minor costs.

Imipenem/cilastatin (1.5 g daily) versus meropenem (3.0 g daily) in patients with intra-abdominal infections: results of a prospective, randomized, multicentre trial.

An open-label prospective, randomized, parallel multicentre study was undertaken to compare the efficacy and tolerability of 1.5 g/day intravenous imipenem/cilastatin with 3 g/day intravenous meropenem in the treatment of intra-abdominal infections. A total of 287 patients were enrolled: 201 patients, divided between the 2 treatment groups, were evaluable. Clinical outcome, bacteriological outcome, untoward microbiological effects, and clinical and laboratory adverse experiences were evaluated. 98% of patients receiving imipenem/cilastatin therapy were cured, with 96% showing eradication of infection. 95% of those on meropenem were cured, with 98% showing eradication. These differences in clinical and bacteriological outcome between the 2 treatments were not statistically significant. Two patients receiving imipenem/cilastatin and 5 receiving meropenem had untoward microbiological effects. There was a 0.7% frequency (1/139 patients) of possibly or probably drug-related clinical or laboratory adverse experiences with imipenem/cilastatin and a 2.7% frequency (4/148) with meropenem. The mean time to defervescence was significantly less for patients in the imipenem/cilastatin treatment group than for those receiving meropenem. This study shows that 1.5 g/day of imipenem/cilastatin is equivalent to 3.0 g/day meropenem in clinical and bacteriological outcome, as well as in incidence of side effects.

Primary gastric lymphoma: a 15-year review.

BACKGROUND/AIM: Between 1976 and 1991, 25 patients underwent surgical therapy for primary gastric lymphoma. Clinical records were reviewed retrospectively to evaluate prognostic factors and impact of treatment on survival. RESULTS: Diagnostic sensitivity of endoscopic biopsy was 68%, positively of barium contrast studies for tumor was 33%. The overall 5-year survival rate was 67.3% (51.7% "free disease"): it was for stage I E 88.9%, for stages II 1E and II 2E respectively 68.6% and 44.4% and for stage IV 33.4%. Patients with tumors smaller than 5 cm had a 5-year survival rate of 80.8% whereas for patients with larger lesions survival rate was 44% (p < 0.05). Patients with low grade malignancy tumors had a 5-year survival rate of 81.9% versus 37.5% for high grade malignancy tumors (p < 0.03). Chemotherapy as adjuvant therapy was used in 17 cases (68%). 53% of them are "free disease" at minimum 4 years from the operation. CONCLUSIONS: We conclude that, surgical management of primary gastric lymphoma is mandatory but a planned multimodality therapy may produce complete remission and long-term "free disease" survival rate even in patients with relapse.

[Anorectal functional study. The state of the art]. / Studio della funzione anorettale. Orientamenti attuali.

Disturbances of anal continence and evacuation are frequent. Numerous techniques are now available to measure anorectal function. There is also a better understanding of the anatomy and physiology of the pelvic floor which has a major role in anorectal function. ANORECTAL MANOMETRY. Manometry of the anal canal is an index of the resistance of sphincters to the passage of faeces. Resting pressure is due mainly to the internal anal sphincter whereas voluntary contraction is due mainly to the external anal sphincter. Anorectal manometry is essential in measuring the length of the anal canal and in establishing the presence of the rectoanal inhibitory reflex. Several techniques are employed to evaluate anorectal manometry which is useful in the investigation of patients with faecal incontinence and constipation. PUDENDAL LATENCIES: Pudendal latencies are valuable in the study of the innervation of the external anal sphincter. Pudendal latencies are measured thanks to the stimulation of the S2-S4 nerves lying in the proximity of the ischial spine through the use of a special glove (St Mark's glove). Prolonged pudendal latencies are typical of neurogenic faecal incontinence but it can be brought about by childbirth, rectal prolapse, obstructed defecation and old age. ELECTROMYOGRAPHY. Electromyography is useful in the study of the function of the pelvic floor. This technique can be performed with single fibre needles which make it possible to measure the action potentials and the fibre density of the muscular fibres. Fibre density is raised in neurogenic faecal incontinence and the action potentials are polyphasic in this condition. Concentric needles are employed to map the anal sphincters and this is useful for evaluating the extent of the damage caused by traumatic events like a third degree tear. ANAL ENDOSONOGRAPHY. Anal ultrasound is very effective in the study of the morphology of the anal sphincters and it requires a rectal probe fitted with a 7-MHz transducer. It is as accurate as electromyography in evaluating the damage to the anal sphincters but it is not painful and it is more acceptable to the patient. DEFECOGRAPHY. This radiological test is a dynamic study of the pelvic floor during defecation. It is very useful for investigating the function and the morphology of the rectum and the pelvic floor during defecation. Important parameters like: the anorectal angle, the opening of the anal canal, the position of the pelvic floor and the descent of the perineum can be evaluated with this test. Defecography is useful in the study of patients with rectal prolapse and constipation. CONCLUSION. All these tests provide extremely useful information on the pelvic floor and are reproducible. They can be of great help in evaluating patients with pelvic floor disorders but they are no substitute for clinical judgement.

[Trends in the incidence of acute appendicitis in Italy during the past 30 years]. / Andamento dell'incidenza dell'appendicite acuta in Italia negli ultimi 30 anni.

The incidence and mortality rate of acute appendicitis for the years 1955 and 1987 were calculated on the basis of data used by ISTAT. In 1955 the incidence was 5.7 per 1000 whereas in 1987 this had fallen to 3.7 per 1000. In both years examined there was a prevalence of females (in 1987 females accounted for 4.3 per 1000 in comparison to 3 per 1000 recorded for for males). In 1987 the lowest incidence was recorded in the over 60 years olds, whereas the highest incidence was in males between 1 and 14 years old (7.57 per 1000) and females between 15 and 24 years old (12.17 per 1000). Mortality diminished from 0.42% in 1955 to 0.05% in 1987. The highest rate of mortality was recorded in those patients over 60 years old (1.5%).

Primary sclerosing cholangitis: an analysis of 37 retrospective cases.

The clinical and laboratory findings of 37 patients with primary sclerosing cholangitis (PSC) were reviewed. Mean age was 43.8 years, sex ratio between males and females was 3:1; IBD was present in 91% of patients with 51% having ulcerative colitis, 23% unclassified colitis and 17% Crohn's disease. Twenty-seven patients (73%) were symptomatic presenting most commonly with fatigue, pruritus and hepato-splenomegaly. Cholangiography revealed abnormalities affecting both extrahepatic and intrahepatic biliary ductal systems in 51.8% of cases, and only the intrahepatic or extrahepatic biliary tree, respectively in 11.1% and in 37% of cases. The last prevalence was very high compared with that previously known. Clinical and biochemical data, when compared between asymptomatics and symptomatics, demonstrated a significant difference only for alkaline phosphatase which increased in the symptomatic group and for prothrombin activity which decreased among symptomatic patients. Nevertheless, predictive value of sALP for the presence of PSC was high when pts were pooled together with a randomly selected group of 36 non-affected persons that underwent ERCP for suspected primary sclerosing cholangitis: sensitivity was 94% and specificity 78%.

[Pharmacokinetics of the biliary excretion of some chemotherapeutic agents in patients with biliary disease]. / Farmacocinetica dell'escrezione biliare di alcuni chemioterapici in pazienti con patologia biliare.

The authors have assessed the concentration of 7 antibiotics in the bile of patients undergoing biliary surgery or carriers of a T tube in the common bile duct. 1 hour preoperatively, 122 patients were administered with the following chemotherapeutic agents: Cefoxitin 2 g i.v.; Cefamandole 2 g i.v.; Ceftriaxone 1 g i.v.; Clindamycin 600 mg i.v.; Amikacin 500 mg i.v.; Gentamycin 160 mg i.v.; Norfloxacin 400 mg by mouth; 30 patients showed obstructive jaundice or obstructed cystic duct. Samples of bile were withdrawn from gallbladder and common bile duct. The same antibiotics were administered to 81 patients carrying a T tube. Samples of bile and serum were collected at baseline and every 30 minutes for 4 hours and subsequently at 12 and 24 hours following administration. 18 patients showed altered liver function tests. The chemotherapeutic agents were tested by the microbiological assay as well as by HPLC. Mean concentration in the gallbladder bile was: Cefoxitin 209 +/- 86 micrograms/ml; Cefamandole 436 +/- 108 micrograms/ml; Ceftriaxone 482.7 +/- 214.84 micrograms/ml; Clindamycin 64 +/- 22 micrograms/ml; Amikacin 5 +/- 1.4 micrograms/ml; Gentamycin 4 +/- 2 micrograms/ml; Norfloxacin 22 +/- 14 micrograms/ml. In the bile of jaundiced patients or with non-visualized gallbladder no antibiotics were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefotetan versus cefoxitin in the treatment of patients with biliary sepsis assessed by a biliary sepsis score.

The authors carried out a study to assess the efficacy of an antibiotic treatment (cefotetan or cefoxitin) in 22 stratified patients with biliary sepsis, at low and high risk. The severity of sepsis was assessed by a biliary sepsis score (B.S.S.). No significant difference in results was observed between the two treatments in low-risk groups (cefotetan 80%, cefoxitin 75% satisfactory), while the difference between the high risk groups was significant (cefotetan 75%, cefoxitin 40% satisfactory). In the low risk group it can be stated that better nutritional and immunological status provide adequate host defences and that the antibiotic treatment is less important in determining surgical outcome. In high risk patients the efficacy of an antibiotic, cefotetan in this case, can significantly improve clinical results.

Biliary pseudocyst. A rare consequence of an iatrogenic lesion of the bile ducts.

A patient with a biliary pseudocyst due to an iatrogenic lesion of the hepatic duct is reported. The pseudocyst caused compression of the bile duct with progressive jaundice. Diagnostic problems and the utility of ERCP and PTC in determining the exact site of the lesion for surgical treatment are reported.

Acute cholangitis: diagnostic and therapeutic problems.

A retrospective study was carried out, analyzing the diagnostic and therapeutic problems in 80 patients with acute cholangitis at the time of hospitalization. 23% of the 17 patients with pus in the bile duct showed Reynolds' pentad, which was observed in 10% of patients with nonsuppurative acute cholangitis. Common bile duct lithiasis was responsible in 80% of cases presenting with Reynolds' pentad and in 66% of postoperative mortality. In 75% of patients with tumors, the clinical picture showed a rapid development following PTC. 79% of patients responded positively to antibiotic therapy with subsequent elective surgery, while in 21% of patients who did not respond to antibiotic therapy, biliary drainage was the treatment of choice. Mortality in patients with shock or hypotension was 30% while it was 17% in those undergoing early (less than 72 hours) surgery. On the basis of the results, it is concluded that, since it is not possible to assess preoperatively whether a patient belongs to the group of suppurative acute cholangitis or to that of nonsuppurative acute cholangitis, the different severity of the clinical picture should be based on clinical and biochemical parameters. The most severe developments were observed in common bile duct lithiasis or in patients with tumors who underwent PTC. In case of failure to respond to antibiotic therapy, decompression was shown to be the most suitable treatment. The mortality rate is related to the severity of the clinical picture (presence or not of shock) as well as to a prompt surgical treatment.