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Biomedical subjects

S Mendoza

Publications and source records attributed to S Mendoza.

89 records · Page 5Linked to original sources
PubMed1966

Electron microscopy of Staphylococcus aureus cell wall lysis.

Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018-2024. 1966.-A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents.

Bacteriolysis↗
PubMedDate not supplied

Somatostatin prevents acute pancreatitis after pancreatic duct sphincter hydrostatic balloon dilation in patients with idiopathic recurrent pancreatitis.

The purpose of this study was to determine whether prophylactic somatostatin infusion can prevent pancreatitis after hydrostatic balloon dilation of the pancreatic duct sphincter segment in 16 patients with idiopathic recurrent pancreatitis. This study demonstrated that prophylactic administration of somatostatin before, during, and after the procedure diminished the incidence and severity of acute pancreatitis. We recommend consideration of such prophylaxis in patients undergoing this procedure.

Acute Disease↗
PubMedDate not supplied

Effect of local instillation of alcohol on sphincter of Oddi motor activity: combined ERCP and manometry study.

The effect of local instillation of alcohol on sphincter of Oddi motor activity was determined by endoscopic manometry. Sphincter of Oddi pressures and motor function were compared in eight cholecystectomized subjects with normal sphincter of Oddi motor function and in four patients with chronic alcoholic pancreatitis. The effect of local instillation of 3 ml of 40% alcohol was compared with water instillation. In cholecystectomized subjects, alcohol produced a significant increase of basal sphincter of Oddi pressure from 21.0 +/- 2.8 mm Hg to 95.8 +/- 83 mm Hg (p less than 0.01) without significant changes in the amplitude, duration, and frequency of phasic contractions. In patients with alcoholic chronic pancreatitis, alcohol instillation resulted in a significant increase of basal sphincter of Oddi pressure from 32.5 +/- 4.8 mm Hg to 225.1 +/- 105 mm Hg without changes in amplitude, duration, and frequency of phasic contractions. Two patients with chronic alcoholic pancreatitis had a tonic contraction of the sphincter of Oddi with transitory and mild epigastric pain. Local instillation of alcohol increases sphincter of Oddi motor activity which may play a role in the pathogenesis of alcoholic pancreatitis.

Adult↗
PubMedDate not supplied

ERCP in the diagnosis of extrahepatic biliary atresia.

This study assessed the usefulness of ERCP in the diagnosis of biliary atresia. We evaluated 57 infants with prolonged cholestasis with abdominal ultrasound, liver biopsy, and ERCP. Using clinical observations alone, 22 infants were thought to have biliary atresia; whereas 35 children were thought to have neonatal hepatitis. The ERCP was performed with a prototype duodenoscope and was successful in all infants except two with biliary atresia. In 20 infants three types of radiological findings consistent with biliary atresia were seen: type 1, no visualization of biliary tree (35%); type 2, opacification of the distal common duct and gallbladder without visualization of the main hepatic duct (35%); and type 3, opacification of the distal common duct, the gallbladder, and a segment of the main hepatic duct with biliary lakes at the porta hepatis (30%). Twenty-five of 35 infants with suspected neonatal hepatitis were excluded because of a liver biopsy that was diagnostic. In the remaining 10 infants the liver biopsy had some features of extrahepatic biliary atresia and ERCP was performed prior to surgery. A normal extrahepatic biliary tree was obtained in all of them. In conclusion, ERCP permits the visualization of the biliary tree in young infants and is useful in selecting those infants who should be considered for exploratory laparotomy.

Biliary Atresia↗
PubMedDate not supplied

ERCP and endoscopic sphincterotomy in infants and children with jaundice due to common bile duct stones.

ERCP was performed in two infants (29 and 62 days old) and eight children (5 to 12 years old) with jaundice due to common bile duct stones. Seven patients had hemolytic anemia and three patients had a family history of gallstone disease. Successful cannulation of the common bile duct demonstrating stones was accomplished in all patients. Four patients had coexisting gallstones and were treated surgically. Six children who had previously undergone cholecystectomy were treated by endoscopic sphincterotomy and stone extraction without complication. We believe that ERCP should be utilized by expert endoscopists in children with evidence of extra-hepatic cholestasis, and endoscopic sphincterotomy should be the treatment of choice in children who have previously undergone cholecystectomy, and who are jaundiced secondary to common bile duct stones.

Child↗
PubMedDate not supplied

Nucleoside transport by perfused human placenta.

Nucleoside transport and metabolism by human placenta was studied using the dual perfusion technique. With [3H] thymidine added to the maternal perfusate and neither perfusate recirculated (steady-state studies) around 40 per cent of the thymidine in the maternal outflow and 50 per cent of the transferred thymidine was degraded. In similar studies with adenosine, over 95 per cent of the nucleoside was degraded. Even with the bolus technique which sharply limits the duration of contact with the placenta, degradation of adenosine was over 95 per cent. Uptake as calculated by the dual-tracer method ([3H] adenosine/[14C] L-glucose) was equally rapid from the maternal and fetal perfusates, was saturable and inhibited by nitrosobenzylthioinosine, consistent with the facilitated diffusion system for nucleosides. Thymidine was taken up at one-third the rate of adenosine. Thymidine in large excess (500 microM) reduced adenosine uptake suggesting a common transporter. Zidovudine, a thymidine analogue used for the treatment of AIDS in which the ribose is modified at the 2' 3' position, did not compete with adenosine for uptake consistent with previous reports that zidovudine is transferred across the placenta by simple diffusion.

Adenosine↗
PubMedDate not supplied

[Double sphincterostomy of pancreatic and choledochal sphincters in the treatment of chronic recurrent pancreatitis].

The treatment of recurrent chronic pancreatitis is controversial. Some patients may have sphincter of Oddi motor abnormalities. Although widely used in the biliary tree, little data is available on endoscopic sphincterotomy of the pancreatic sphincter. This report describes 5 patients with recurrent chronic pancreatitis, who had pancreatic sphincterotomy for hypertensive sphincter of Oddi. Four patients continue long-term follow-up with marked reduction of chronic pain of attacks of recurrent pancreatitis. It is concluded that endoscopic sphincterotomy of the pancreatic sphincter may improve pain in chronic pancreatitis and may obviate the need for surgery.

Adolescent↗
PubMedDate not supplied

[Incidence of Helicobacter pylori in Barrett esophagus].

In Barrett's esophagus the normal squamous epithelium of the mucosa is replaced by columnar epithelium. In this study, we evaluated the incidence of Helicobacter pylori in 28 patients with Barrett's esophagus. In 11 patients (39%) H. Pylori was present and all of them had the bacteria in the gastric antrum. From the 17 patients without H. pylori in the Barrett's mucosa, in 4 (22%) the bacteria was present in the gastric antrum. In conclusion, H. pylori infects the esophagus only when the esophageal mucosa is replaced by the columnar epithelium. The clinical significance of this finding is yet to be determined.

Adult↗
PubMedDate not supplied

[Usefulness of endoscopic retrograde cholangiopancreatography in diagnosis of choledochal cysts in children].

We report 11 infants with choledochal cyst confirmed during surgery. In none of the patients an abdominal mass was palpated during physical examination. In 10 (91%) of the patients, ERCP showed the cyst. Ultrasound was positive in 82% (9/11) of the cases. Two patients had acute relapsing pancreatitis with severe anatomical abnormalities at the pancreatobiliary junction. Multiple biliary lithiasis were seen in four cysts. ERCP is of significant value in establishing the diagnosis, defining anatomic abnormalities and complications. ERCP should be the procedure of choice in patients with suspected choledochal cyst.

Child↗
PubMedDate not supplied

[Comparison of urease test (CLOtest) and histology in the diagnosis of Campylobacter pylori].

Campylobacter pylori has been implicated in the pathogenesis of peptic ulcer, non-ulcer dyspepsia and chronic gastritis. C. pylori produces large amounts of urease which has been used as a biochemical support to identify the microorganism. In this study, we described the use of a rapid urease test (CLOtest) to detect C. pylori. In 46 consecutive patients, biopsy of fundus and antrum were obtained for histology and CLOtest. All specimens showed chronic gastritis. In 22 patients (48%) C. pylori was identified either by histology or CLOtest. In 18 patients (39%) CLOtest was positive and in 16 patients (35%) histology was positive. In 12 patients (26%) C. pylori was identified by both tests. There was no difference in relation to the presence of C. pylori in fundus and antrum. However, in 2 patients (4%) C. pylori was positive in fundus and negative in antrum. In 9 patients (20%) C. pylori was positive in antrum and negative in fundus. CLOtest is a simple, sensitive and rapid test that enables the endoscopist to diagnose C. pylori infection in the endoscopy room.

Adult↗
PubMedDate not supplied

Used of a guide-wire inserted catheter for acute peritoneal dialysis.

Peritoneal dialysis was performed in 18 children using a new guide-wire inserted catheter technique. Catheter insertion was complicated only by mild bleeding in one patient. The catheters drained well immediately after insertion in 17 of the 18 patients. Catheters were used for an average of 6 days, with a range up to 16 days. Dialysate volumes could be increased quickly in most patients. Late complications were leakage (2), peritonitis (4) and obstruction (3). Leakage did not interfere with dialysis. The peritonitis episodes, which occurred between days 6 and 16 of dialysis, resolved satisfactorily with appropriate antibiotic therapy. The guide-wire catheter can be inserted and used for short term peritoneal dialysis in children.

Acute Kidney Injury↗
PubMedDate not supplied

Status of the p53, Rb and MDM2 genes in canine osteosarcoma.

The key role of p53 and Rb alterations in human osteosarcoma is clear. For example, osteosarcoma is common in individuals inheriting mutant p53 or Rb genes. Osteosarcoma in dogs is similar to humans by histology, site, gender ratio and several other biological parameters. To study whether this similarity extends to the molecular level, 21 canine osteosarcomas were analyzed for alterations of p53, Rb and MDM2. MDM2 is a normal cell protein which antagonizes p53, amplification is seen in some human sarcomas. The gross structure of the p53, Rb and MDM2 genes was examined by Southern blotting. No deletions or rearrangements of the p53 or Rb genes were detected. The absence of gross gene alterations affecting these tumor suppressor genes is a significant difference between the disease in dogs and humans, since rearrangements or deletions of the p53 or Rb genes occur in 20-30 per cent of human osteosarcomas. The MDM2 gene appeared to be duplicated in one canine tumor but no cases of significant amplification were detected. Expression of normal Rb was detected in all cases. Mutations of the p53 gene were found in 38 percent of canine osteosarcomas. Analysis of mutations revealed a predominance of spontaneous mutation. These finding emphasize the key role that alterations of p53 have in the development of osteosarcoma in dogs and humans.

Animals↗