Structural and functional roles of the N1- and N3-protons of psi at tRNA's position 39.

Pseudouridine at position 39 (Psi(39)) of tRNA's anticodon stem and loop domain (ASL) is highly conserved. To determine the physicochemical contributions of Psi(39)to the ASL and to relate these properties to tRNA function in translation, we synthesized the unmodified yeast tRNA(Phe)ASL and ASLs with various derivatives of U(39)and Psi(39). Psi(39)increased the thermal stability of the ASL (Delta T (m)= 1.3 +/- 0.5 degrees C), but did not significantly affect ribosomal binding ( K (d)= 229 +/- 29 nM) compared to that of the unmodified ASL (K (d)= 197 +/- 58 nM). The ASL-Psi(39)P-site fingerprint on the 30S ribosomal subunit was similar to that of the unmodified ASL. The stability, ribosome binding and fingerprint of the ASL with m(1)Psi(39)were comparable to that of the ASL with Psi(39). Thus, the contribution of Psi(39)to ASL stability is not related to N1-H hydrogen bonding, but probably is due to the nucleoside's ability to improve base stacking compared to U. In contrast, substitutions of m(3)Psi(39), the isosteric m(3)U(39)and m(1)m(3)Psi(39)destabilized the ASL by disrupting the A(31)-U(39)base pair in the stem, as confirmed by NMR. N3-methylations of both U and Psi dramatically decreased ribosomal binding ( K (d)= 1060 +/- 189 to 1283 +/- 258 nM). Thus, canonical base pairing of Psi(39)to A(31)through N3-H is important to structure, stability and ribosome binding, whereas the increased stability and the N1-proton afforded by modification of U(39)to Psi(39)may have biological roles other than tRNA's binding to the ribosomal P-site.

Proton-NMR investigation of the heme cavity in the cyanomet derivative of the cooperative homodimeric hemoglobin from Scapharca inaequivalvis.

The active-site structure of the paramagnetic cyanomet complex of the cooperative homodimeric hemoglobin from Scapharca inaequivalvis has been investigated by solution homonuclear NMR. In spite of the large size (32 kDa), the residues on the key proximal F- and distal E-helices could be sequence-specifically assigned and placed in the heme pocket in a manner common to diamagnetic systems. These backbone assignments were greatly facilitated by the significant dispersion of backbone chemical shifts by the highly anisotropic paramagnetic susceptibility tensor of the low-spin ferric state. The remainder of the residues in contact with the heme are assigned based on unique contacts to the heme predicted by the crystal structure and the observations of scalar connectivities diagnostic for the residues. The magnitude of the dipolar shifts for non-ligated residues was used to determine the anisotropy and orientation of the paramagnetic susceptibility tensor, and the major axis found tilted from the normal in a manner similar to that found for the Fe-CO unit in the crystal structure. The combination of NOESY inter-residue and heme-residue contacts, paramagnetic-induced relaxation and correlation between observed and dipolar shifts provide a description of the heme cavity in cyanomet Hb that is essentially the same as found in the carbonmonoxy Hb crystal structure. The pattern of both the heme methyl dominant contact shifts and the heme meso-proton dominant dipolar shifts are shown to be consistent with the orientation of the axial His. It is concluded that the present homonuclear NMR methods allow effective solution structure determination in the cyanomet form for dimeric Hb and suggest profitable extension to the tetrameric vertebrate hemoglobins.

1H-, 13C- and 31P-NMR studies of dioctanoylphosphatidylcholine and dioctanoylthiophosphatidylcholine.

Coupling constants and chemical shifts were measured for dioctanoylphosphatidylcholine and its thio analogue in a CDCl3/CD3OD solvent mixture. Replacing the bridging oxygen atom of the CH-CH2-O-P portion of the phosphatidylcholine molecule with a sulfur atom affects chemical shifts and coupling constants in the glycerol backbone portion of the molecule as well as in the choline head group region. Preferred conformations about selected bonds in the phospholipids were determined from the vicinal 1H-1H, 31P-1H and 31P-13C coupling constants. A reduction of the 31P T2* (effective spin-spin relaxation time) for the thio analogue, as well as changes in the relative chemical shifts of 13C nuclei in the acyl chains, suggest a somewhat greater degree of aggregation for the thio analogue. The quadrupolar coupling constant 1J(14N-13C) for the choline methyls of either analogue, however, indicates that aggregation of these phospholipids in the CDCl3/CD3OD solvent mixture is not significant. Differences in conformation between dioctanoylphosphatidylcholine and its thio analogue may be responsible for their differences in chemical and physical properties.

Reduction and binding of arsenate and dimethylarsinate by glutathione: a magnetic resonance study.

By observing the chemical shifts of the proton and carbon-13 nuclei of reduced glutathione, the interactions of arsenate, arsenite and dimethylarsinate with this tripeptide have been characterized. These spectral studies show the reduction and complexation of arsenic to be a two-step process. Initially, the oxidation of 2 mol of glutathione reduces arsenate to arsenite. Then, 3 mol of glutathione are consumed in the formation of a glutathione-arsenite complex. Similar experiments with arsenite identified a (glutathione)3-arsenite complex; however, no oxidized glutathione was detected. The arsenite binding site in the glutathione-arsenite complex is the cysteinyl sulfhydryl. The glutathione-arsenite complex is stable over the pH range from 1.5 to 7.0-7.5. At higher pH, dissociation occurs releasing reduced glutathione. For a glutathione to dimethylarsinate ratio of 3, oxidized glutathione is also coupled with a reduction to trivalent dimethylarsinous acid, prior to the formation of a 1:1 glutathione-dimethylarsinite complex. The role of reduced glutathione in the metabolism of arsenic is consistent with the previously described effects of this agent on the organismic toxicity of arsenic.

[The role of angiography in cryptogenic submesocolic digestive tract bleeding]. / Ruolo dell'angiografia nelle emorragie digestive sottomesocoliche criptogenetiche.

Three cases of chronic gastrointestinal bleeding are described; the Authors emphasize the important role of mesenteric arteriography in establishing site and nature of bleeding. The review of international literature shows a success rate between 41 and 73% of cases studied with this method after negativity of other diagnostic procedures.

[A rare case of Meckel's diverticulum perforation]. / Un raro caso di perforazione del diverticolo di Meckel.

Meckel's diverticulum is a pathology not rarely found everyday clinical medicine especially when it present with one of its complications. The specific diagnosis is a bit difficult to put because of the low sensibility and specificity of symptoms of diagnostic and instrumental techniques used. The reported case shows a rare type of complication constituted by the phlogosis of Meckel's diverticulum, itself due to an extraneous thing ingested by the patient. The authors discuss the entity of the manifestations of this pathology and highlight every aspects.

[Giant bladder calculus. Report of a clinical case]. / Calcolosi gigante della vescica. Osservazione di un caso clinico.

The authors describe a case of giant vesical calculus in an 89 year old patient. The diagnosis, as in the other cases reported in the international literature, was made after a series of laboratory and instrumental exams, for groups reported by the patient in the lower abdomen. Operated for the removal of the vesical calculus, he was considered healed after a fortnight. The vesical calculus has a mixed composition and it weighs about 380 grams. The revision of the literature shows the various chemical composition of the vesical calculus that does not permit to identify a common aetiology. It is not possible to demonstrate if the formation of this kind of calculus is primary (in the urinary bladder) or if it is proper of the high urinary tract or mixed. The most recurrent causes being various and different confirm the mixed aetiopathologic theory. The diagnosis, often casual, is made thanks to the most common diagnostic exams; as it is difficult to make a complete cystoscopic control because the bladder is almost completely occupied by the lithiasic formation. The surgical therapy consists of a epicystotomy with a following removal of the calculus. In literature, moreover, cases treated with extra-body lithotripsy are not reported, on the contrary ot happens daily for the lithiasis of the high urinary tract.

[Laparovideocholecystectomy]. / La laparovideocolecistectomia.

The authors present the guidelines which have been followed to introduce into their own Surgical Division an alternative method to cholelithiasis treatment: laparovideocholecystectomy (l.v.c.). They point out how the directions for use of the new surgical method, in place of the traditional laparectomic technique, must be limited to non-complicated cholelithiasis cases, especially in the initial learning stages. That sets the global "morbility" of the above said l.v.c. beneath the cholecystectomy performed with traditional technique. In addition, they point out the sure economic advantages at social and contributions level arriving at the conclusion that l.v.c. is the best treatment for Gallstones.

[Cancer of the gallbladder]. / Il cancro della colecisti.

Carcinoma of the gallbladder is the most frequent neoplasia of the biliary tract with an incidence of 2.5-4.4 cases for every 100,000 inhabitants; it more often affects females and elderly patients (60-70 years). It is an extremely malignant tumour with an often fatal prognosis owing to both its site and the generally late diagnosis; the majority of patients in fact undergo surgery at an advanced stage of the disease when surgery is only palliative. At the Surgical Division of S. Massimo Hospital in Penne (PE) a total of 897 operations on the gallbladder and biliary tract were performed between 1988 and 1994, revealing 21 cases of carcinoma of the cholecyst (2.3%). Sixteen patients were female (male-female ratio 1:3.2) with a mean age of 67.8 years (range 58-83 years). These patients were divided into 5 stages according to the UICC-1992 classification: 80.9% of cases were stage 3-4. Diagnosis was performed intraoperatively in 2 patients, whereas in 3 cases cancer had been diagnosed by the anatomo-pathologist. A total of 3 simple cholecystectomies were performed, 4 were associated with hepatic resection and lymphadenectomy of the hilus and hepatoduodenal ligament; surgery was enlarged in 2 cases due to the involvement of adjacent organs. After exploratory laparotomy, palliative surgery was performed in the remaining 12 patients in the form of biliary and derivation. Four system were implanted for intra-arterial chemotherapy. The most frequently found histological type was adenocarcinoma (76.2%). The mean survival rate of patients who died was 7.6 months. Six of the operated patients are still alive, of whom only one with a follow-up of 4 years. In conclusion, the authors agree with those who consider carcinoma of the gallbladder generally fatal in view of the rarity of early diagnosis and the difficulties of performing radical therapy.

[Laparoalloplasty by the Rives' technique for the treatment of large ventral hernias. Ten-year experience]. / Laparoalloplastica secondo Rives per il trattamento dei grandi laparoceli. Dieci anni di esperienza.

The problems of the surgery of bulky laparoceles began to find concrete solutions with the introduction of materials of synthesis that can be used to reinforce or to substitute the abdominal wall. Despite that, the ideal prosthesis has still not been found, the Dacron (Mersilene), the Polypropylene (Marlex, Prolene) and PTFE (Goretex) are today considered the best materials for the alloplasty. The authors describe their experience in matter of bulky laparocels treated with the technique of Rives. 49 patients have been operated, using Dacron in 44 cases and Polypropylene in 5. They had no mortality and no relapse, while the most frequent complication was 6 seromas, all resolved with conservative therapy. In their series 3 infections of the subcuticular occurred more of which required the removal of the prosthesis.

[Internal hernias. Description of 2 cases]. / Le ernie interne. Descrizione di due casi.

The authors describe two cases of recent observed internal-hernia, regarding in the first case the right para-duodenal dimple, and in the second a mesenteric breach. They report the clinic presentation and the diagnostic and therapeutic approach compared with the data deriving from the international literature. A complete clinical classification of the internal-hernia is illustrated showing the different clinical signs. The respective symptomatology that in the initial phases of this pathology is not too evident, shows that the internal hernia should always be held in due consideration at the moment of diagnosis because the consequent mortality due to complications such as intestinal-gangrene is rather high.

[Cancer of the gastric stump. Our experience]. / Il cancro del moncone gastrico. Nostra esperienza.

The authors discuss their experience of six cases of cancer of the gastric stump observed by them in the period from 1988 to 1992 inclusive. All the patients were operated; five total gastrectomies and a gastric re-resection were effected. In association also the spleen was removed in four patients, in one of them a hepatic metastasectomy and a distal pancreasectomy were effected. In the discussion the problems concerning the diagnostic and therapeutic implications with some references to the more likely etiopathogenetic theories were dealt with.

[Extraperitonealization of the liver in the Chilaiditi syndrome]. / Extraperitoneizzazione del fegato per sindrome di Chilaiditi.

The Chilaiditi syndrome or viscero hepato diaphragmatic interposition is a rare anomaly. The authors describe one case they observed. Even if it is often asymptomatic, it may manifest also by recurrent sub-occlusion or occlusion. Only a few patients need corrective surgical operation. The operation of choice is hepatic extra-peritonealization, which after replacement of the dislocated gastroenteric tract, brings the superior face of the liver again into direct contact with the related diaphragmatic dome.

[Latero-terminal anastomosis in colorectal surgery using a mechanical stapler. Technical note]. / L'anastomosi latero-terminale con suturatrici meccaniche in chirurgia colo-rettale. Nota tecnica.

Following a discussion of the various methods of colorectal anastomosis in cancer surgery, the Authors describe a technical variant using a mechanical stapler in a high rectal location. The rapidity of anastomosis as well as the decreased risk of dehiscence, fistula and stenosis are underlined.

[The selective use of intraoperative cholangiography in video laparoscopic cholecystectomy]. / L'utilizzo selettivo della colangiografia intraoperatoria nella colecistectomia videolaproscopica.

Intraoperative cholangiography, a diagnostic method through images introduced in to clinical use in 1932, has recently become a different technical support from that attributed by traditional surgery and it has got a different diagnostic meaning with the introduction of video surgery. The authors used it in 54 of 194 patients submitted to a CVL, always making use of the trans-cystic access, with a percentage of success of 82.6%. It was not possible in 8 patients due to the complete section of the cystic duct during the work (3 cases) and the impossibility of introducing the catheter (5 cases). There is still no common agreement about the opportunity to use IC daily: the authors think selective use is better preceded by a careful clinical laboratory instrumental preoperative study to find patients with the common duct stone. Besides, they are of the opinion that a rigorous surgical technique is fundamental to reduce the lesions of the VBP that there are not in their experience.

[Laparoscopic deroofing of non parasitic posterolateral liver cyst. Technical considerations]. / Fenestrazione laparoscopica di cisti non parassitaria posterolaterale del fegato. Considerazioni tecniche.

Laparoscopic deroofing of the solitary non parasitic cysts of the liver is a safe and effective procedure. This technique allows a wide access for surgical treatment of cysts localized in segments II, III, IVb, V, and VIII of the liver. On the contrary, the posterior segments, VI and VII, and the segment IVa, are difficult to approach laparoscopically. This report describes a laparoscopic technique used in treating 3 cases of symptomatic solitary cysts of the posterior segments of the liver. The patients were placed in the left lateral position. The fenestration treatment was easy and the mobilization of the right hepatic lobe was not required. At one year follow-up, neither postoperative complications nor recurring episodes were observed.

[Lumbar hernia of Grynfeltt's quadrilateral space. Apropos a case]. / Ernia lombare del quadrilatero di Grynfelt. A proposito di un caso.

The authors discuss a case of Grynfeltt's quadrilateral lumbar hernia in an 85-year-old patient. These rather rare hernias can be classified as Grynfeltt's hernias of the superior lumbar space, as Petit's inferior lumbar space and as diffused hernias concerning the whole hip. In our case this hernia was located in the superior lumbar space and it was delimited on the upper part by the 12th rib and by the serratus posterior-inferior muscle; in the lower part by the internal oblique muscle and by the lumbar quadratus muscle. Surgical treatment was effected by plastic surgery with synthetic material put in the extra-peritoneum space and fixed by serum-muscular stitches. Postoperative control effected after a month from the operation proves a good keeping of the plastic surgery reconstruction with total disappearance of the hernia.

[Splenectomy for hematologic disease. Mini-invasive versus traditional technique]. / La splenectomia per malattie ematologiche. Tecnica mininvasiva e tradizionale.

BACKGROUND: This study aimed to compare the safety, efficacy and clinical benefits of laparoscopic splenectomy (LS) to open splenectomy (OS) in patients with hematologic disorders. EXPERIMENTAL DESIGN: prospective study; SETTING: II Department of Surgery, Santa Maria Nuova Hospital, Reggio Emilia and III Department of Surgery, Santo Spirito Hospital Pescara; PATIENTS: 48 consecutive adult patients underwent splenectomy; 30 patients under-went LS and 18 OS. Perioperative characteristics, outcomes, complications and costs were comparatively analyzed. RESULTS: Mean age was 35.3 years in the LS group, and 40.8 in the OS group. Mean spleen size was 11.7 cm in the LS group and 15.2 cm in the OS group. Accessory spleens were found in 5 patients in the LS group and in 4 patients in the OS group; 4 conversions to laparotomy occurred in the LS group. A total of 4 complications occurred in 3 patients of the LS; 9 complications occurred in 5 patients of OS group. Mean surgical time was 141.5 minutes for LS and 89.7 minutes for OS (p<0.005). Mean postsurgical stay was 5.8 days in the LS group and 8.5 days in the OS group (p<0.005). Response rates were similar in both groups. CONCLUSIONS: LS is comparable to OS in terms of efficacy and safety and it is associated with a shorter hospital stay. LS should become the technique of choice for treatment of intractable benign hematologic disease.

[Branchial carcinoma]. / II carcinoma branchiale.

The Authors report three cases of epidermoidal carcinoma arising from a congenital cyst of the anterolateral region of the neck. This type of tumor, rarely found in daily practice, arises from a degenerate branchial tissue and differential diagnosis often includes nodal involvement from systemic neoplasias. However, diagnostic criteria of such diseases are well defined; furthermore the rarity of branchial carcinoma is opposed to the high frequency of metastatic lymph nodes deriving from tumors with similar histological aspects located in other sites which could alter the real percentage of branchial tumor manifestation.

Importance of modified nucleosides to the structure and function of tRNAs.

Although a few modifications are found in DNA, 93 modified nucleosides have been found in the various RNAs. For the most part, the chemistry and structure that modified nucleosides, individually and in combination, uniquely contribute to DNA or RNA function have yet to be explained. However, there are ten physicochemical contributions that can be attributed to modified nucleosides. Of particular interest is the increasingly documented relationship between the presence of modified nucleosides in tRNAs, and the site and affinity of Mg2+ binding to RNA and its effect on function.