Extracorporeal shock wave lithotripsy of gall stones: an in vitro comparison between an electrohydraulic and a piezoceramic device.

A comparative study of the effectiveness of two types of lithotripter in fragmenting gall bladder stones is reported. The machines used were a Piezolith 2300, which generates shock waves by the piezoceramic principle, and a Dornier MPL 9000, which produces the shock waves by underwater spark discharge. With each machine, corresponding stones of 45 pairs of weight and volume matched calculi (median volume 0.5 cm3, median diameter 10.5 mm) obtained at cholecystectomy were treated. All stones were successfully disintegrated (fragments smaller than 2 mm) with up to 5400 (median 628) shocks with the Piezolith and 3450 (median 428) shocks with the MPL 9000 lithotripters. With the Piezolith, operating at the highest power setting, a 1.65 fold median higher number of shocks was required for stone fragmentation than with the MPL 9000 at a medium power setting. Stone volume seemed to be the only determinant which affected ease of fragmentation; composition and density of the stones as assessed by computed tomography did not seem to be governing factors.     

Gastric and duodenal polyps in familial adenomatous polyposis: a prospective study of the nature and prevalence of upper gastrointestinal polyps.

One hundred patients with familial adenomatous polyposis have prospectively undergone gastroduodenoscopy to identify and characterise polyps found. Forty six patients had polyps in the stomach or duodenum. Thirty five patients had adenomas (33 in duodenum, two in stomach) and 26 patients had fundic gland polyps. Some of these patients had polyps in the stomach and the duodenum. Adenomas in the duodenum were present in 33% of patients studied with Gardner's syndrome variant (p = 0.04). Adenomas were also more common in older patients. As adenomas may be a precursor of adenocarcinoma, routine surveillance of the stomach and duodenum with gastroduodenoscopy is recommended in patients affected with familial adenomatous polyposis.     

Percutaneous endoscopic gastrostomy in 41 patients: indications and clinical outcome.

Percutaneous endoscopic gastrostomy, under local anaesthetic, was successfully used in 40 out of 41 patients referred for nutritional support. The indications were neurological disorders of swallowing in 32 patients, head and neck cancer in four patients and supplemental feeding in a miscellaneous group of five patients. The main complications of this procedure were one failed insertion and one peritubal infection. At prospective follow-up, the tube continued to function in 16 patients (seven at home) a mean of 184 days post-insertion (range 6-610 days). In 11 patients resumption of swallowing at a mean of 122 (20-390) days allowed tube removal. Thirteen patients died from their disease, a mean of 96 (12-320) days post-insertion. Patient tolerance and patient and carer satisfaction have been excellent and early results suggest that recovery of speech and swallowing in acute neurological disorders may be enhanced. Percutaneous endoscopic gastrostomy should be performed in all patients referred for a gastrostomy and should be considered in all patients requiring long-term tube feeding.     

Prostaglandins and CGRP release from cardiac sensory nerves

Summary (1) The possible influence of Prostaglandins (PG) E₁ and I₂ as well as ischaemia, ouabain and bradykinin on the outflow of calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (LI) from the guinea-pig heart was studied in vitro. (2) Exposure to PGE₁ (10^–5 M), but not PGI₂ (10^–5 M), induced an increased outflow, suggesting release of CGRP-LI. PGE₁ simultaneously increased the contractile force and heart rate while no effects were observed on perfusate volume or outflow of NPY-LI. PGI₂ had no effect on contractile parameters or coronary flow. In separate experiments on capsaicin-pretreated animals, the stimulatory effects of PGE₁ on heart rate and contractile force remained unchanged while no increased CGRP-LI outflow was detectable. (3) Ouabain, bradykinin and reperfusion after total stop-flow ischaemia was associated with an indomethacin-resistant increase in perfusate levels of CGRP-LI but not of NPY-LI. While ouabain markedly increased the contractile force, exposure to bradykinin or ischaemia did not induce any clear-cut changes in contractile force or heart rate. (4) Capsaicin-exposure evoked a markedly increased outflow of CGRP-LI but not of NPY-LI in combination with an increase in heart rate and a decrease in contractile force. Repeated administration of capsaicin induced tachyphylaxis. The stimulatory effects of capsaicin on CGRP-LI outflow and heart rate, but not the negative inotropic effect, did not occur in capsaicin-pretreated animals. (5) It is concluded that PGE₁, but not PGI₂, can activate cardiac capsaicin-sensitive fibres as revealed by increased outflow of CGRP-LI. The cardiostimulatory effects induced by PGE₁ are not related to CGRP release, however. A possible prostaglandin link in the CGRP-LI released by ouabain, bradykinin or ischaemia seems unlikely. Send offprint requests to: A. Franco-Cereceda at the above address     

Alpha-ketoacids stimulate rat renal cysteine conjugate beta-lyase activity and potentiate the cytotoxicity of S-(1,2-dichlorovinyl)-L-cysteine

Renal cysteine conjugate beta-lyase (beta-lyase) catalyzes the bioactivation of nephrotoxic cysteine S-conjugates. beta-Lyase activity is present in both renal cytosolic and mitochondrial fractions, and, although the cytosolic beta-lyase is identical to glutamine transaminase K, the mitochondrial beta-lyase has not been characterized. Because beta-lyase is a pyridoxal phosphate (PLP)-dependent enzyme, pyridoxamine phosphate (PMP) formation may occur during the metabolism of cysteine S-conjugates. In this study, the effects of alpha-ketoacids, which may convert the PMP form of the enzyme to the pyridoxal phosphate form, on the metabolism and cytotoxicity of cysteine S-conjugates were examined; the PMP enzyme is catalytically inactive in beta-elimination reactions, but is catalytically active in transamination reactions. Both alpha-keto-gamma-methiolbutyrate (KMB) and alpha-ketobutyrate enhanced the metabolism of S-(2-benzothiazolyl)-L-cysteine (BTC) to 2-mercaptobenzothiazole by rat renal cytosol or mitochondria. KMB and phenylpyruvate potentiated both the cytotoxicity of S-(1,2-dichlorovinyl)-L-cysteine (DCVC) in isolated rat renal proximal tubular cells and the inhibition of mitochondrial respiration produced by DCVC. These results are consistent with the formation of PMP during the renal cytosolic or mitochondrial metabolism of cysteine S-conjugates. Mitochondrial beta-lyase was previously localized in the outer membrane. To examine whether beta-lyase activity is present in mitoplasts, but in the PMP form, the effects of KMB on the metabolism of BTC to 2-mercaptobenzothiazole and on the DCVC-induced inhibition of state 3 respiration in mitoplasts were studied. The majority of the mitochondrial beta-lyase activity was present in the outer membrane, and the specific activity of the outer membrane beta-lyase was greater than that of the mitoplast beta-lyase. KMB produced equivalent stimulation of beta-lyase activity in intact mitochondria, in mitochondrial outer membranes, and in mitoplasts and potentiated DCVC-induced inhibition of respiration in intact mitochondria, but not in mitoplasts. These results provide additional evidence for the central role of beta-lyase in the bioactivation of nephrotoxic cysteine S-conjugates.