Search PubMed⌕ Search

Biomedical subjects

Y T Ko

Publications and source records attributed to Y T Ko.

At least 37 records · Page 2Linked to original sources
PubMed1993

Approximations in the measurement of surface tension on the oscillating bubble surfactometer.

This paper examines two factors, shape deformation and surface viscosity, that affect measurements of surface tension of lung surfactants with the oscillating bubble surfactometer. At lower surface tensions, the compressed bubble in this apparatus becomes deformed to an oblate ellipsoid that cannot be analyzed rigorously using the simplified (spherical) Laplace equation to calculate surface tension from interfacial pressure drop. However, for the small air bubbles present in this apparatus, analysis with more general equations for ellipsoids of revolution shows that deformation effects are limited to extremely low surface tensions, and the absolute error from the spherical approximation is minimal in practice. In contrast, this was not the case for the effects of surface dilational viscosity in oscillating bubble calculations. Direct measurements and values from the literature indicated that the surface dilational viscosities of lung surfactant, dipalmitoyl phosphatidylcholine, and palmitic acid were sufficient to give substantial errors if their effects on interfacial pressure drop were neglected during dynamic cycling. Surface tension calculations at maximum and minimum radii on the oscillating bubble apparatus remain accurate, because the time derivative of radius becomes zero and viscous effects vanish. However, surface tensions determined at points other than these extremes of bubble size should be interpreted with caution.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Sonographic findings of intestinal tuberculosis.

Sonograms in 41 patients with intestinal tuberculosis were analyzed. The sonographic findings of intestinal tuberculosis were thickening of the wall in the ileum, cecum, or ascending colon (or in more than one of these). We detected the wall thickening in 38 cases by sonography (detection rate, 93%). The ileum was the most frequent site of involvement. The patterns of bowel wall thickening were diffuse in 30 cases and focal in eight cases and were concentric in 28 cases and eccentric in six cases. The associated findings were ascites, lymphadenopathy, omental cake, and cecal spasm in order of decreasing frequency. The sonographic findings are not specific for the diagnosis of intestinal tuberculosis, but when noted in the appropriate clinical situation would be of great help in the diagnosis of intestinal tuberculosis.

Adult↗
PubMed1992

Multiple lymphomatous polyposis of the gastrointestinal tract--a report of two cases with immunohistochemical studies.

We describe two cases of multiple lymphomatous polyposis in the gastrointestinal tract from the esophagus to the rectum. Clinical findings, histopathologic and immunohistochemical findings in paraffin embedded tissue are discussed. It is important to recognize this rare form of gastrointestinal lymphoma because of the prognostic and therapeutic implications.

Antigens, CD↗
PubMed1992

Sonographic detection of duodenal ulcer.

Using a wall thickness of greater than 5 mm for the first portion of the duodenum as the criterion for the sonographic diagnosis of duodenal ulcer, we studied the value of sonography in detecting this lesion. Endoscopy (88 patients) and upper gastrointestinal barium studies (12 patients) were used as the gold standards for the diagnosis. The study included 100 patients in whom gastrointestinal disease was suspected (20 with duodenal ulcer and 80 with normal findings). Of the 20 duodenal ulcers verified by endoscopy or upper gastrointestinal series, 13 patients had duodenal wall thickening, six had normal wall thickness, and one was nondiagnostic. Of the 80 subjects with normal findings on endoscopy or upper gastrointestinal series, 73 patients had a normal duodenum, four had wall thickening, and three were nondiagnostic. Considering the four nondiagnostic cases as sonographic errors, there were six false-negative cases and four false-positive cases (a sensitivity of 65%, specificity of 91%, positive predictive value of 76%, and negative predictive value of 92%). Our results show that sonography is not sufficiently sensitive to be used as a screening test, nor is it specific for duodenal ulcer, but a thickened duodenal wall of over 5 mm on sonography warrants additional work-up.

Duodenal Ulcer↗
PubMed1991

Sonographic findings in tuberculous peritonitis of wet-ascitic type.

Sonograms in 46 patients with tuberculous peritonitis of the wet-ascitic type were analysed retrospectively. The ascites was clear in 24 patients (52%). There were fixed membranes, septa and debris in eight patients (17%), floating debris in six patients (13%), mobile strands or membranes in four patients (9%), and fixed septa in four patients (9%). The patients were divided into two groups depending on the amount of ascites: small amount of ascites with clear fluid in eight patients (17%), and moderate or large amount of ascites with clear or complex fluid in 38 patients (83%). Associated findings were omental 'cake' (26%), hepatomegaly (24%), thickened mesentery with adherent small bowel loop (22%), splenomegaly (20%), pleural effusion (17%), lymphadenopathy (13%), and thickening of the ileal wall (7%). The sonographic findings are not specific for tuberculous peritonitis, but may give valuable information to prevent unnecessary laparotomy.

Abdomen↗
PubMed1991

Afferent loop syndrome: sonographic findings in seven cases.

We studied the sonographic findings in seven patients in whom afferent loop obstruction was first detected by sonography. All seven subsequently were proved at surgery to have afferent loop syndrome. The causes of the obstruction included internal hernia (n = 3), cancer recurrence (n = 2), marginal ulcer (n = 1), and development of cancer at the anastomosis site (n = 1). In all cases, the dilated afferent loop was seen on sonography as a tubular structure in the upper abdomen crossing transversely over the midline. The distal end of the afferent loop could be traced toward the anastomosis. The probable cause of the syndrome was predicted on the basis of sonography in two of three patients with cancer at the anastomosis. Our experience suggests that afferent loop syndrome can be diagnosed sonographically on the basis of the detection, location, and shape of the dilated afferent loop.

Adult↗
PubMed1990

Medial extent of the posterior renal fascia. An anatomic and computed tomography study.

To study the medial extent of the posterior renal fascia and the perirenal space, the authors dissected two cadavers and reviewed 50 computed tomographic (CT) abdominal scans. The results demonstrated that the medial extent of the posterior renal fascia depends on the level in a vertical direction and its relationship to the kidney which varies at different levels. At the renal hilus, the fascia inserts posteromedially to the fascia of the quadratus lumborum along its lateral margin; more cranially, the line of insertion is more lateral, onto the diaphragmatic fascia; more caudally, the line of insertion is more medial, inserting onto the anterior surface of the quadratus lumborum. Therefore the posteromedial insertion of the posterior renal fascia extends medially, from the more laterally placed diaphragmatic fascia, to the lateral margin of the quadratus lumborum and then to the anterior surface of the quadratus lumborum, depending on the anatomic level. The clinical implication of these findings are discussed.

Cadaver↗
PubMed1990

Clonorchiasis of the pancreas.

Three patients with pancreatic clonorchiasis were examined with endoscopic retrograde pancreatography. On each of the three cases there was diffuse irregular dilatation of tributaries of the pancreatic duct in the pancreatic tail. The main pancreatic duct and tributaries draining into the body and head portion were not dilated. A sonogram from one patient showed diffuse enlargement of the pancreas, especially the tail. All three patients showed typical cholangiographic findings of hepatic clonorchiasis, namely diffuse peripheral intrahepatic bile duct dilatation with no or minimal dilatation of the extrahepatic duct. When the tributaries of the pancreatic duct in the tail of the pancreas are diffusely dilated, in the appropriate clinical setting, pancreatitis caused by Clonorchis sinensis should be considered.

Aged↗
PubMed1990

Sonographic detection of pneumoperitoneum in patients with acute abdomen.

We describe five patients who presented with an acute abdomen in whom pneumoperitoneum was first detected by sonography. All five subsequently were proved to have a perforated viscus. In all cases, the pneumoperitoneum was seen as an echogenic line with a posterior ring-down or reverberation artifact between the anterior abdominal wall and the anterior surface of the liver. The finding was shown best in the right upper quadrant with the patient in the left lateral decubitus position. The echoes caused by the pneumoperitoneum overlapped the echoes of the lung during inspiration, but the echoes were separate during expiration. The probable cause of pneumoperitoneum was determined with sonography in four of the five patients: three had perforation of duodenal ulcer and one had perforation of gastric cancer. The fifth patient had a perforated ileum, which was not evident on the sonogram. Our experience with these patients suggests that the detection of pneumoperitoneum on sonography in patients with an acute abdomen is an important sign of a perforated viscus.

Abdomen, Acute↗
PubMed1990

Oriental cholangiohepatitis: sonographic findings in 48 cases.

Oriental cholangiohepatitis is characterized by recurrent attacks of abdominal pain, fever, chill, and jaundice and grossly dilated extrahepatic and intrahepatic ducts containing soft, pigmented stone and pus. Sonograms were studied in 48 patients in whom the diagnosis was later proved during surgery (n = 34) or on the basis of clinical and laboratory findings and endoscopic retrograde cholangiography (n = 14). The sonographic findings included intrahepatic and/or extrahepatic bile duct stones (n = 47); moderate to severe dilatation of the extrahepatic ducts with relatively mild or no dilatation of intrahepatic bile ducts (n = 41); localized dilatation of the lobar or segmental bile ducts, especially the left hepatic lobe (n = 16); and gallstones (n = 22). Our experience suggests that the preoperative diagnosis of oriental cholangiohepatitis can be strongly suggested by sonographic findings.

Adult↗
PubMed1990

Anatomic relationship of intrahepatic bile ducts to portal veins.

To assess the anatomic relationship between the intrahepatic bile ducts and corresponding portal veins, we studied anterior-posterior relationship of the segmental bile ducts to the accompanying portal veins using sonograms and cadavers. On sonograms of the 64 segments in 16 patients with biliary dilation, the segmental bile ducts lay anterior to the corresponding portal veins in 34%, posterior in 39%, superior in 2%, tortuous in 13%, and undetermined in 13%. The relationship was inconsistent in terms of hepatic segments and thus bile ducts lay anterior to the portal vein in one segment and posterior in the other segment within the same liver. Sagittal sections in 11 segments of the 3 cadaveric livers revealed that the bile ducts were anterior to the corresponding portal veins in 1 segment, posterior in 2 segments, superior in 5 segments, anterosuperior in 1 segment, and posterosuperior in 2 segments. It is concluded that, contrary to the common belief, there is no constant anterior-posterior relationship between the intrahepatic bile ducts and the corresponding portal veins.

Bile Duct Diseases↗
PubMed1990

Sonographic sliding sign in localization of right upper quadrant mass.

Sonographic sliding sign is the observation of dynamic motion of a mass against adjacent organs during respiratory movement or extrinsic pressure. We applied this sign for prospective study in nine patients, each of whom had a large posterior right upper abdominal mass arising from the liver, kidney, or adrenal gland. The sign was found to be very reliable as a criterion for the localization of the origin of the mass in all patients except in the following two cases: a Wilm's tumor that invaded the retroperitoneum and posterior abdominal wall was regarded as a retroperitoneal tumor invading the kidney; and in the other one, an adrenal pheochromocytoma, the sliding sign against the liver and the right kidney was equivocal. In conclusion, judicious use of the sonographic sliding sign will greatly assist in the localization of a large right upper abdominal mass, especially when there is a paucity or lack of retroperitoneal fat.

Abdominal Neoplasms↗
PubMed1989

Clonorchiasis: sonographic findings in 59 proved cases.

Clonorchiasis is a parasitic disease of the bile ducts that occurs in endemic areas after ingestion of the raw flesh of freshwater fish. We analyzed the sonographic findings in 59 patients with clonorchiasis, suspected prospectively from sonographic findings and proved subsequently by demonstration of eggs in their stools. Diffuse dilatation of the small intrahepatic bile ducts with no or minimal dilatation of the large intra- and extrahepatic ducts was observed in all cases. The extrahepatic ducts were patent throughout in all except one case. This characteristic finding reflects diffuse intrahepatic bile duct obstruction and resultant proximal dilatation caused by an adult worm or aggregates of worms, as worms reside diffusely in the medium and small intrahepatic bile ducts. Cholangitis and multifocal periductal fibrosis with proximal dilatation may play an additional role. Increased echogenicity of the intrahepatic bile duct wall was present in 39 cases (66%), reflecting cholangitis and periductal fibrosis. In 17 cases (29%), floating or dependent, discrete, nonshadowing, intraluminal, echogenic foci caused by adult worms in the bile were demonstrated in the gallbladder. These echogenic foci were distinguished from stones because they were fusiform, weak in echogenicity, and floated with a change in position. Clonorchiasis should be considered when sonography discloses the characteristic pattern of bile duct dilatation with increased wall echogenicity and nonshadowing, discrete, echogenic foci in the gallbladder lumen.

Adult↗
PubMed1988

Superior aspect of the perirenal space: anatomy and pathological correlation.

To study the anatomy of the superior aspect of the perirenal space, we analysed 50 computed tomographic (CT) scans with reference to the anatomy of Gerota's fascia, and dissected five cadavers laying special emphasis on the ascent of Gerota's fascia. We also reviewed 10 scans of patients with a large lesion in the right upper abdomen regarding localisation of the lesion. We conclude that Gerota's fascia does not cover the upper portion of the kidney and adrenal gland so that the superior aspect of the perirenal space is open towards the upper abdominal extraperitoneal space. Thus, a large lesion arising from the right adrenal gland or kidney easily invaginates the liver through the bare area mimicking a hepatic lesion, and vice versa. This explains the difficulty in localising a large lesion in the right upper abdomen.

Humans↗
PubMed1987

Ultrasound changes of the gallbladder wall in cholecystitis: a sonographic-pathological correlation.

To assess the pathological basis of the changes seen on ultrasound examination of the gallbladder wall in cholecystitis, the appearances of the gallbladder wall were analysed in 17 patients with acute cholecystitis and 27 patients with chronic cholecystitis, and correlated with the pathological specimens removed at surgery. A thin echo reduced layer within the echogenic gallbladder wall corresponds to a complex of subserosal oedema, haemorrhage and inflammatory cell infiltration, or to muscular hypertrophy. Indistinctness or a low echogenicity rind along the inner margin represents mucosal sloughing or obliteration of the mucosal folds. Uniformly decreased echogenicity of the wall is caused by severe inflammatory change with sloughing of the mucosa or obliteration of the mucosal folds. These ultrasound signs are considered to be valuable signs of cholecystitis.

Acute Disease↗
PubMed1987

The inferior accessory hepatic fissure: sonographic appearance.

The inferior accessory hepatic fissure, a coronal or parasagittal fissure through the parenchyma of the posterior segment of the right hepatic lobe, was observed sonographically in 15 of 2000 patients. The fissure was seen as a thin, echogenic membrane stretching downward from the right branch of the portal vein to the inferior surface of the right hepatic lobe. On cadaveric sections, the fissure was an invagination of peritoneum directed laterally and slightly posteriorly from the medial inferior surface of the right hepatic lobe below the porta hepatis.

Humans↗
PubMed1984

Role of biotin in the production of lysine by Brevibacterium lactofermentum.

To investigate the role of biotin in lysine production, Brevibacterium lactofermentum ATCC 21086 was grown in an acid-hydrolysed whey permeate medium with and without added biotin. Added biotin stimulated lysine production and growth of B. lactofermentum. Five micrograms of biotin/100 ml was the optimum level of addition. Biotin increased the uptake of 14C-glucose and affected fatty acid composition of cell wall lipids. Cell walls of test organisms contained less 16:0 and more 18:2 fatty acids than did those from control cells. However, biotin did not substantially affect the phospholipid content of cell walls and whole cells, and the intracellular free lysine level. It was concluded that the promotive effect of biotin in lysine production might be due to the stimulatory effect of biotin on the growth of B. lactofermentum. Alteration of the cell surface caused by biotin did not appear to affect the release or accumulation of lysine.

Biotin↗