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Biomedical subjects

S S Wu

Publications and source records attributed to S S Wu.

At least 19 recordsLinked to original sources
PubMed2002

Linkage mapping of sex-specific differences.

Most current linkage analyses assume identical fractions of meiotic recombination between homologous marker loci of the two sexes. This assumption is not realistic, because considerable sex-related differences have been observed in recombination fraction. In this paper, a general EM-based algorithm is presented to estimate sex-specific recombination fractions for a mixed set of molecular markers segregating differently in a full-sib family derived from two heterozygous parents. The asymptotic variances of the estimates of linkage specifically for each of the parents are evaluated using a numerical analysis based on information functions. This approach will have important implications for precise gene mapping based on sex-specific linkage maps.

Algorithms↗
PubMed2001

Ascitic fluid carcinoembryonic antigen and alkaline phosphatase levels for the differentiation of primary from secondary bacterial peritonitis with intestinal perforation.

BACKGROUND/AIMS: In cirrhotic patients, spontaneous bacterial peritonitis (SBP) may be difficult to distinguish from secondary peritonitis with occult intestinal perforation; Runyon's criteria (based on ascitic fluid glucose, protein and lactate dehydrogenase levels) are sensitive but not specific. Ascitic fluid carcinoembryonic antigen (CEA) and alkaline phosphatase (AP) are potential markers for secondary peritonitis. METHODS: Ascitic fluid CEA and AP levels were prospectively compared among three subject groups--cirrhotic patients with sterile ascites, cirrhotic patients with SBP, and patients (cirrhotic and non-cirrhotic) with perforation-related secondary peritonitis. RESULTS: The secondary peritonitis group (n = 38 including 11 cirrhotic patients) had significantly higher mean CEA and AP levels than the SBP (n = 34) and sterile ascites patients (n = 63). Of secondary peritonitis patients, 92% fulfilled predetermined criteria (either CEA >5 ng/ml or AP >240 units/l) versus only 12% of SBP patients; sensitivity was 92% and specificity 88% for differentiating secondary peritonitis from SBP. Runyon's criteria had a sensitivity of 97% and specificity of 56%. Stratification of secondary peritonitis patients by the presence or absence of cirrhosis did not alter our results. CONCLUSIONS: Ascitic fluid CEA or AP elevations appear to be sensitive and specific markers for perforation-related secondary peritonitis in cirrhotic as well as non-cirrhotic patients.

Adult↗
PubMed2001

Milk of calcium cholelithiasis in children.

Milk of calcium bile is uncommon and occurs mainly in the adult population. The authors report on 2 children, each having a distinct clinical history and presentation, and each with milk of calcium bile/calculi possessing differing chemical composition and highly notable gross morphology. J Pediatr Surg 36:644-647.

Calcium Carbonate↗
PubMed2001

A multivalent pairing model of linkage analysis in autotetraploids.

Polyploidy has been recognized as an important step in the evolutionary diversification of flowering plants and may have a significant impact on plant breeding. Statistical analyses for linkage mapping in polyploid species can be difficult due to considerable complexities in polysomic inheritance. In this article, we develop a novel statistical method for linkage analysis of polymorphic markers in a full-sib family of autotetraploids. This method is established on multivalent pairings of homologous chromosomes at meiosis and can provide a simultaneous maximum-likelihood estimation of the double reduction frequencies of and recombination fraction between two markers. The EM algorithm is implemented to provide a tractable way for estimating relative proportions of different modes of gamete formation that generate identical gamete genotypes due to multivalent pairings. Extensive simulation studies were performed to demonstrate the statistical properties of this method. The implications of the new method for understanding the genome structure and organization of polyploid species are discussed.

Algorithms↗
PubMed2001

17-beta estradiol can reduce secondary ischemic damage and mortality of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a unique disorder commonly occurring when an aneurysm ruptures, leading to bleeding and clot formation, with a higher incidence in females. To evaluate the influence of 17-beta estradiol (E2) in the outcome of subarachnoid hemorrhage, SAH was induced by endovascular puncture of the intracranial segment of internal carotid artery in 15 intact females (INT), 19 ovariectomized females (OVX), and 13 ovariectomized female rats with E2 replacement (OVX + E2). Cerebral blood flow was recorded before and after SAH. All animals were decapitated immediately after death or 24 hours after SAH for clot area analysis. Brains were sliced and stained with 2,3,5-triphenyltetrazolium chloride (TTC) for secondary ischemic lesion analysis. The cortical cerebral blood flow (CBF), which was measured by a laser-Doppler flowmeter, decreased to 29.6%+/-17.7%, 22.8%+/-8.3%, and 43.5%+/-22.9% on the ipsilateral side (P = 0.01), and decreased to 63.4%+/-14.1%, 57.4%+/-11.0%, and 66.6%+/-17.9% on the contralateral side (P = 0.26) in INT, OVX, and OVX + E2, respectively. The subcortical CBF, which were measured by the H2 clearance method, were 7.77+/-12.03, 7.80+/-8.65, and 20.58+/-8.96 mL 100 g(-1) min(-1) on the ipsilateral side (P < 0.01), and 21.53+/-2.94, 25.13+/-3.01, and 25.30+/-3.23 mL 100 g(-1) min(-1) on the contralateral side in INT, OVX, and OVX + E2, respectively. The mortality was 53.3%, 68.4%, and 15.4% in INT, OVX, and OVX + E2, respectively (P = 0.01), whereas no significant difference in clot area was noted among the groups. The secondary ischemic lesion volume was 9.3%+/-8.4%, 24.3%+/-16.3%. and 7.0%+/-6.4% in INT, OVX, and OVX + E2, respectively (P < 0.01). This study demonstrated that E2 can reduce the mortality and secondary ischemic damage in a SAH model without affecting the clot volume.

Animals↗
PubMed2001

Brassica rapa has three genes that encode proteins associated with different neutral lipids in plastids of specific tissues.

Plastid lipid-associated protein (PAP), a predominant structural protein associated with carotenoids and other non-green neutral lipids in plastids, was shown to be encoded by a single nuclear gene in several species. Here we report three PAP genes in the diploid Brassica rapa; the three PAPs are associated with different lipids in specific tissues. Pap1 and Pap2 are more similar to each other (84% amino acid sequence identity) than to Pap3 (46% and 44%, respectively) in the encoded mature proteins. Pap1 transcript was most abundant in the maturing anthers (tapetum) and in lesser amounts in leaves, fruit coats, seeds, and sepals; Pap2 transcript was abundant only in the petals; and Pap3 transcript had a wide distribution, but at minimal levels in numerous organs. Immunoblotting after sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that most organs had several nanograms of PAP1 or PAP2 per milligram of total protein, the highest amounts being in the anthers (10.9 microg x mg(-1) PAP1) and petals (6.6 microg x mg(-1) PAP2), and that they had much less PAP3 (<0.02 microg x mg(-1)). In these organs PAP was localized in isolated plastid fractions. Plants were subjected to abiotic stresses; drought and ozone reduced the levels of the three Pap transcripts, whereas mechanical wounding and altering the light intensity enhanced their levels. We conclude that the PAP gene family consists of several members whose proteins are associated with different lipids and whose expressions are controlled by distinct mechanisms. Earlier reports of the expression of one Pap gene in various organs in a species need to be re-examined.

Amino Acid Sequence↗
PubMed2001

A maximum likelihood-based method for mining major genes affecting a quantitative character.

In this article, we present a maximum likelihood-based analytical approach for detecting a major gene of large effect on a quantitative trait in a progeny population derived from a mating design. Our analysis is based on a mixed genetic model specifying both major gene and background polygenic inheritance. The likelihood of the data is formulated by combining the information about population behaviors of the major gene during hybridization and its phenotypic distribution densities. The EM algorithm is implemented to obtain maximum likelihood estimates for population and quantitative genetic parameters of the major locus. This approach is applied to detect an overdominant gene governing stem volume growth in a factorial mating design of aspen trees. It is suggested that further molecular genetic research toward mapping single genes affecting aspen growth and production based on the same experimental data has a high probability of success.

Algorithms↗
PubMed2001

Management of multiple level spondylolysis of the lumbar spine in young males: a report of six cases.

The most common procedure for surgical treatment of lumbar spondylolysis is intertransverse processes spinal arthrodesis with instrumentation. However, this procedure is associated with significant morbidity on long-term follow up. Direct repair of spondylolysis is an alternative method for preservation of motion segment and anatomic continuity in young adults with multiple level spondylolysis. From 1992 through 1998, six soldiers with a diagnosis of multiple level spondylolysis who complained of persistent low back pain were treated in our hospital. Spondylolysis involved two levels in five cases and three levels in one case. All patients underwent serial roentgenography of the lumbar spine and a staged pars interarticularis infiltration test with bupivacain 0.5%. Five patients underwent direct repair of the pars interarticularis defects with hook screws, translaminar screws, and bone graft, while one patient received conservative treatment. All surgically treated patients had either good or excellent results at a mean of 34.4 months follow-up. One patient who was treated nonsurgically still complained of sport restriction at 16 months follow-up. Direct repair of multiple pars interarticularis defects after a positive staged pars infiltration test can restore anatomic stability, relieve back pain, and preserve a greater range of motion of the lumbar spine in young patients with intact disc height.

Adult↗
PubMed2000

Truncus arteriosus and other lethal internal anomalies in Goltz syndrome.

An infant girl of 36 weeks gestational age was found to have cardiovascular and other lethal internal anomalies in addition to characteristic external abnormalities of focal dermal hypoplasia (Goltz syndrome). The internal anomalies included truncus arteriosus type II with truncal origin of hypoplastic pulmonary arteries, cardiac ventricular septal defect, severe hypoplasia of lungs and pulmonary veins, massive diaphragmatic hernia, and absence of the right kidney. Such a combination of severe anomalies has not been reported previously in Goltz syndrome.

Abnormalities, Multiple↗
PubMed2000

Dietary habits and right-sided colonic diverticulosis.

PURPOSE: In Asian populations, there is a high prevalence of right-sided colonic diverticulosis, the cause of which is uncertain. It is suspected that dietary habits may interact with a congenital predilection to cause this condition. To evaluate the relationship between long-term dietary habits and the prevalence of right-sided diverticulosis in the general population, we performed a retrospective case-control study. METHODS: We reviewed the records of 3,105 screening colonoscopies performed on healthy, asymptomatic adults. All cases of right-sided diverticulosis were selected, and a similar number of gender-matched and age-matched controls with negative colonoscopies were randomly sampled from the same cohort. All case and control subjects were interviewed by a single-blinded nurse to establish their dietary habits during the past decade, in addition to other demographic characteristics. Based on consumption frequency, they were assigned to one of three diet classes for each of three food categories of interest: meat, vegetable, and fruit products. Staple foods such as rice were not included. Odds ratios were then calculated using multivariate conditional logistic regression and tests for trend were performed. RESULTS: A total of 86 cases of right-sided diverticulosis were included, whereas 106 controls were randomly selected. There was a marked association between meat consumption frequency and right-sided diverticulosis, with a trend P value of <0.01 and an odds ratio of 24.81 between the most and least frequent consumers of meat products. CONCLUSIONS: The prevalence of right-sided diverticulosis is strongly positively associated with past meat consumption frequency. There is no association with vegetable or fruit consumption frequency, laxative use, supplemental fiber intake, smoking, or family history.

Adult↗
PubMed2000

Bacterial peritonitis after elective endoscopic variceal ligation: a prospective study.

OBJECTIVE: Endoscopic variceal ligation is becoming the therapy of choice for esophageal varices, replacing endoscopic variceal sclerotherapy. The latter is associated with a 5-53% incidence of port-procedural bacteremia and a 0.5-3% incidence of peritonitis, whereas the former carries a 3-6% risk of bacteremia. However, the incidence of peritonitis after variceal ligation has not been well studied. This prospective study is designed to investigate the risk of developing bacteremia and bacterial peritonitis after elective endoscopic variceal ligation. METHODS: Sixty-seven patients with esophageal varices and ascites secondary to liver cirrhosis underwent elective endoscopic variceal ligation. Before the procedure, ascitic fluid was drawn under ultrasound guidance and sent for cell counts, Gram stain, and cultures. Two to 4 days afterward, a repeat ascitic fluid sample was sent for the same studies whether or not the patient had symptoms or signs suggestive of infection. Blood cultures were drawn both immediately before and after the endoscopic ligation procedure. RESULTS: Of 67 subjects, 11 developed asymptomatic bacteremia with Gram-positive commensals. However, none of them progressed to peritonitis. Two patients who did not have bacteremia developed mild febrile peritonitis with Escherichia coli and were successfully treated with oral antibiotics. No other infectious complications were noted. CONCLUSIONS: There is a significant risk of asymptomatic bacteremia and bacterial peritonitis after elective variceal ligation. The peritonitis does not seem to be related to the bacteremia, as patients who had bacteremia did not develop peritonitis and vice versa. In addition, the involved organisms were quite different. Unlike the bacteremia, postligation peritonitis may be a consequence of severe liver cirrhosis rather than the procedure itself. The clinical significance of postligation bacteremia is doubtful. With regard to peritonitis, in our opinion the use of prophylactic antibiotics should be reserved for patients with Child's C class cirrhosis, a recent history of variceal bleeding, a past history of bacterial peritonitis, or a comorbid immunosuppressive condition.

Adult↗
PubMed2000

8 french transradial coronary interventions: clinical outcome and late effects on the radial artery and hand function.

BACKGROUND: Limited information is available on the effects of 8 French (Fr) transradial procedures on radial patency. In addition, the effects of radial procedures and radial occlusion on hand function are unknown. METHODS: Two groups were recruited: twenty-four patients who had undergone 26 transradial 8 Fr interventions and 16 patients who had undergone 16 transradial 6 Fr procedures. At 1 year, radial patency, hand strength and hand endurance were measured. RESULTS: No major adverse cardiac events or vascular complications were noted in either group. Late radial occlusion was noted in 2/18 (11%) 8 Fr patients and 3/16 (19%) 6 Fr patients (p = ns). There were no differences in the 8 Fr group between the catheterized and uncatheterized radial arteries for diameter (3.2 +/- 1.1 mm versus 3.3 +/- 0.7 mm, respectively; p = NS) or volumetric flow (55 +/- 51 ml/minute versus 57 +/- 45 ml/minute, respectively; p = NS). No differences in hand strength or hand endurance were seen between the catheterized and uncatheterized arms in the 8 Fr group, between the 8 Fr and 6 Fr groups, or between occluded and non-occluded patients. CONCLUSION: Transradial use of 8 Fr guiding catheters appears to be feasible and safe in highly selected patients, albeit associated with a low incidence of silent radial occlusion. Additionally, neither the use of 8 Fr sheaths nor the presence of radial artery occlusion appear to adversely affect hand strength or endurance.

Aged↗
PubMed1999

The predominant protein on the surface of maize pollen is an endoxylanase synthesized by a tapetum mRNA with a long 5' leader.

In plants, the pollen coat covers the exine wall of the pollen and is the outermost layer that makes the initial contact with the stigma surface during sexual reproduction. Little is known about the constituents of the pollen coat, especially in wind-pollinated species. The pollen coat was extracted with diethyl ether from the pollen of maize (Zea mays L.), and a predominant protein of 35 kDa was identified. On the basis of the N-terminal sequence of this protein, a cDNA clone of the Xyl gene was obtained by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequence of the 35-kDa protein shared similarities with the sequences of many microbial xylanases and a barley aleurone-layer xylanase. The 35-kDa protein in the pollen-coat extract was purified to homogeneity by fast protein liquid chromatography and determined to be an acidic endoxylanase that was most active on oat spelt xylan. Northern and in situ hybridization showed that Xyl was specifically expressed in the tapetum of the anther after the tetrad microspores had become individual microspores. Southern hybridization and gene-copy reconstruction studies showed only one copy of the Xyl gene per haploid genome. Analyses of the genomic DNA sequence of Xyl and RNase protection studies with the transcript revealed many regulatory motifs at the promoter region and an intron at the 5' leader region of the transcript. The Xyl transcript had a 562-nucleotide (nt) 5' leader, a 54-nt sequence encoding a putative signal peptide, a 933-nt coding sequence, and a 420-nt 3'-untranslated sequence. The unusually long 5' leader had an open reading frame encoding a putative 175-residue protein whose sequence was most similar to that of a microbial arabinosidase. The maize xylanase is the first enzyme documented to be present in the pollen coat. Its possible role in the hydrolysis of the maize type II primary cell wall (having xylose, glucose, and arabinose as the major moieties) of the tapetum cells and the stigma surface is discussed.

Amino Acid Sequence↗
PubMed1999

Steryl esters in the elaioplasts of the tapetum in developing Brassica anthers and their recovery on the pollen surface.

The tapetum cells in the developing anthers of Brassica napus contained abundant elaioplasts, which had few thylakoid membranes but were packed with globuli of neutral esters. Of the neutral esters, the major ester group possessed mainly 24-methylenecholesterol, 31-norcycloartenol, 24-dehydropollinastanol, and pollinastanol esterified to 18:3 and other unsaturated and saturated fatty-acyl moieties. The minor ester group had a dominant component tentatively identified as 12-dehydrolupeol esterified to mostly 18:0, 16:0, and 20:0 fatty-acyl moieties. The elaioplasts also contained a high proportion (16% w/w of total lipids) of monogalactosyldiacylglycerols (MGDG). This is the first report of plastids having steryl esters as the predominant lipids. We propose that the globuli contain steryl esters and are stabilized by surface MGDG and structural proteins. The tapetosomes, the other abundant lipid-containing organelles in the tapetum, possessed triacylglycerols (TAG) as the predominant lipids. At a late stage of anther development, the minor group of neutral esters and MGDG of the elaioplasts, as well as the TAG of the tapetosomes, were degraded. Steryl esters similar to those of the elaioplasts were recovered from the pollen surface and were the major lipids of the pollen coat. The pollen coat steryl esters and proteins could be extracted with moderately polar or nonpolar solvents. These proteins, which were mostly fragments of oleosins derived from the tapetosomes, had a high proportion of lysine (13 mol %). The possible functions of the steryl esters and the proteins on the pollen surface are discussed.

Brassica↗
PubMed1999

Isolated gastric tuberculosis of the cardia.

BACKGROUND: Isolated gastric tuberculosis is extremely rare, especially in the subcardiac region, where the low pH, high motility and absence of lymphoid tissue result in an unfavourable environment for the development of tuberculous lesions. METHODS AND RESULTS: Here we present a case of isolated gastric tuberculosis in the gastric cardia with no evidence of pulmonary involvement. Our patient was a young man with vague gastrointestinal symptoms and no previous history of tuberculosis. His condition was first detected on upper endoscopy as a raised subcardiac ulcer similar in appearance to a submucosal tumour. An endoscopic forceps biopsy showed the presence of caseating granulomata and acid-fast bacilli. The lesion resolved completely with 12 months of oral anti-tuberculosis therapy. CONCLUSIONS: This case illustrates the need for a high index of suspicion in order to diagnose this rare condition, as it can present in patients with no particular risk factors or symptoms. Once diagnosed, a complete cure can often be achieved with a course of oral anti-tuberculosis medication, with surgery being reserved for severely symptomatic or refractory lesions.

Adult↗