Differential contribution of specific working memory components to mathematics achievement in 2nd and 3rd graders

The contribution of the three core components of working memory (WM) to the development of mathematical skills in young children is poorly understood. The relation between specific WM components and Numerical Operations, which emphasize computation and fact retrieval, and Mathematical Reasoning, which emphasizes verbal problem solving abilities in 48 2nd and 50 3rd graders was assessed using standardized WM and mathematical achievement measures. For 2nd graders, the central executive and phonological components predicted Mathematical Reasoning skills; whereas the visuo-spatial component predicted both Mathematical Reasoning and Numerical Operations skills in 3rd graders. This pattern suggests that the central executive and phonological loop facilitate performance during early stages of mathematical learning whereas visuo-spatial representations play an increasingly important role during later stages. We propose that these changes reflect a shift from prefrontal to parietal cortical functions during mathematical skill acquisition. Implications for learning and individual differences are discussed.

Functional heterogeneity of inferior parietal cortex during mathematical cognition assessed with cytoarchitectonic probability maps

Although the inferior parietal cortex (IPC) has been consistently implicated in mathematical cognition, the functional roles of its subdivisions are poorly understood. We address this problem using probabilistic cytoarchitectonic maps of IPC subdivisions intraparietal sulcus (IPS), angular gyrus (AG), and supramarginal gyrus. We quantified IPC responses relative to task difficulty and individual differences in task proficiency during mental arithmetic (MA) tasks performed with Arabic (MA-A) and Roman (MA-R) numerals. The 2 tasks showed similar levels of activation in 3 distinct IPS areas, hIP1, hIP2, and hIP3, suggesting their obligatory role in MA. Both AG areas, PGa and PGp, were strongly deactivated in both tasks, with stronger deactivations in posterior area PGp. Compared with the more difficult MA-R task, the MA-A task showed greater responses in both AG areas, but this effect was driven by less deactivation in the MA-A task. AG deactivations showed prominent overlap with lateral parietal nodes of the default mode network, suggesting a nonspecific role in MA. In both tasks, greater bilateral AG deactivation was associated with poorer performance. Our findings suggest a close link between IPC structure and function and they provide new evidence for behaviorally salient functional heterogeneity within the IPC during mathematical cognition.

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.

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.

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.

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.

Hepatocellular ubiquitin expression in alpha1-antitrypsin deficiency

Studies of the ubiquitin-proteasome system in alpha1-antitrypsin (AAT) deficiency have been performed using only biochemical and molecular biology techniques on human cells as well as on AAT-deficient transduced cell lines. The objective of our study was to assess the immunohistochemical and topographic features of ubiquitin in the livers of AAT-deficient children with and without active liver disease. Fourteen cases of AAT deficiency were retrieved from our archives, along with 10 control liver specimens obtained from autopsies of age-matched children with no clinical, gross anatomic, or histologic evidence of liver disease. Twelve of 14 cases of AAT deficiency were cirrhotic explanted livers from transplantations procedures. Two cases were noncirrhotic liver biopsies from asymptomatic patients. Periodic acid-Schiff (PAS) histochemistry and AAT immunostains were performed on all AAT-deficient liver specimens to verify the diagnosis. Immunohistochemistry with polyclonal ubiquitin antibodies was performed on all specimens. Ubiquitin immunoreactivity was present in all AAT livers while control livers were consistently negative or weakly reactive. In cirrhotic livers, ubiquitin immunoreactivity was strongest in the cytoplasm whereas the characteristic PAS-positive, diastase-resistant cytoplasmic granules appeared nonreactive. However, not all cirrhotic livers showed this pattern. Some were only focally positive (<5% of hepatocytes). In asymptomatic patients, ubiquitin staining was diffuse and moderate to prominent, and evenly distributed within individual hepatocytes and lobules. We therefore conclude that the ubiquitin-proteasome pathway is operative in the hepatocytes of AAT-deficient livers, as illustrated by the study of ubiquitin immunoreactivity. However, some AAT-deficient livers are only focally immunoreactive for ubiquitin. This may indicate an intrinsic defect of the ubiquitin-proteasome system in some patients.

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.

Hypercellular/heterotopic ganglia in omphalomesenteric duct remnants

Omphalomesenteric duct remnants (ODR) including Meckel diverticula often present with symptoms of bowel obstruction. Their histologic features are varied and include heterotopic gastrointestinal mucosa and/or pancreatic tissue within the wall. Abnormalities of the submucosal plexus of Meissner, however, have not been documented in the literature. Thus, we have examined a number of ODR for evidence of ganglion abnormalities. Fifty-three cases of ODR were retrieved from our archives, along with 25 nonduodenal small bowel control specimens obtained from autopsies of patients without clinical or pathologic evidence of enteropathy. Histologic criteria for the diagnosis of abnormal hypercellular/heterotopic ganglia (HHG) in ODR were defined as a single submucosal ganglion/plexus containing > 10 neurons, or > 5 submucosal ganglions per high-power (x 40) field, or heterotopic ganglion cells within the muscularis mucosa or the lamina propria. HHG, histologically indistinguishable from intestinal neuronal dysplasia type B, were found in more than half of the ODR (ODR: 51.9%, n = 50 vs. control: 4%, n = 25, P = 3.6 x 10(-6), particularly those excised for obstructive complications (ODR with acute abdomen: 65.7%, n = 35, vs. ODR without acute abdomen: 33.3%, n = 15, P = 0.035). HHG were present in equal numbers of inflamed and noninflamed ODR (inflamed: 53.6%, n = 28, vs. noninflamed: 59.1%, n = 22, P = 0.70). A similar incidence was found in ODR with heterotopia and without (with heterotopia: 61.1%, n = 18, vs. without: 53.1%, n = 32, P = 0.59). ODR frequently contained HHG histomorphologically similar to those found in intestinal neuronal dysplasia, type B (IND-B). The overrepresentation of HHG in symptomatic ODR patients suggests an association with bowel obstruction. The data did not demonstrate a relationship with either inflammation or heterotopia.

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.

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.

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.

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.

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.

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.

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.

Congenital gastrointestinal pacemaker cell tumor

The interstitial cells of Cajal complex within the gut wall function as a pacemaker to direct peristalsis. Their neoplastic counterpart is the gastrointestinal pacemaker cell tumor, a spindle and/or epithelioid cell mesenchymal tumor previously known as gastrointestinal stromal tumor or incorrectly called leiomyosarcoma in some cases of older reports. Although numerous cases of gastrointestinal leiomyosarcomas have been documented in the English-language literature, no pediatric case of gastrointestinal stromal tumor or gastrointestinal pacemaker cell tumor has, to our knowledge, been recorded. Herein, we report a case of congenital gastrointestinal pacemaker cell tumor confirmed by immunohistochemistry and electron microscopy in a full-term male newborn.

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.

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.

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.

Risk factors for postoperative femoral fracture in cementless hip arthroplasty

The objective of this study was to evaluate the incidence of and risk factors for femoral fracture in patients who underwent cementless hip arthroplasty during a 3-year period. Several predisposing factors have been reported; we tried to find another predictive indicator that could be recognized preoperatively. The records of all patients who underwent cementless hip arthroplasty from December 1993 to December 1996 were reviewed. The characteristics and clinical features (including age, gender, diagnosis, geometry of the proximal femur, and quality of bone) of the patients who had fractures were compared with those of patients who did not have fractures. During the 3-year study, 425 patients underwent a total of 454 cementless hip arthroplasties. There were 16 postoperative fractures (3.5%, 16 patients). Patients who suffered femoral fracture were significantly older than patients without fracture (65.6 +/- 10.9 yr vs 52.6 +/- 16.2 yr, p < 0.001). The fracture group had poorer preoperative bone quality compared with the nonfracture group (3.3 +/- 0.6 vs 3.8 +/- 0.7, Singh's Index of Osteoporosis, p < 0.01). The canal flare index of the proximal femur was significantly lower in the fracture group than in the nonfracture group (3.3 +/- 0.40 vs 3.8 +/- 0.7, p < 0.01). Our results indicate that old age and osteoporosis affect the likelihood of periprosthetic femoral fractures, and that a low flare index is a predictive indicator of femoral fracture. These factors should be taken into account during preoperative planning, and cemented arthroplasty should be considered for patients with these risk factors.

Operative repair of symptomatic spondylolysis following a positive response to diagnostic pars injection

From 1989 to 1996, 275 patients (245 male and 20 female) with back pain symptoms and spondylolysis of the lumbar spine were reviewed. All patients were evaluated by a protocol that included nonoperative treatment, bone scan, and pars injection. Only those whose symptoms failed nonoperative measures, showing negative bone scan and positive pars injection, were regarded as candidates for surgical management. Pars injection with Marcaine was done, and there were 93 cases with a positive response of reproducing symptoms and symptom relief. Patients then received autogenous bone grafting and internal fixation of the pars interarticularis defect. The internal fixation devices used included translaminar screws (AO 3.5 cancellous screw) for the most frequent level of L5, hook screws for levels above L4, and augmentation with wire for cases with concomitant spinal bifida occulta. The average age of the surgical group (85 male and 8 female) was 23 years (range: 19-35 years). After a follow-up averaging 30.4 months (range: 24-48 months), fusion results were 87%. Clinical results of 85 cases (91.3%) were excellent to good; 8 cases were fair; there were no poor cases. Direct repair of the pars defect by internal fixation and bone grafting was done to preserve involved motion segment and to prevent abnormal stresses at adjacent levels. These procedures seemed to be clinically effective.

Constituents of the tapetosomes and elaioplasts in Brassica campestris tapetum and their degradation and retention during microsporogenesis

In Brassica anthers during microsporogenesis, the tapetum cells contain two abundant lipid-rich organelles, the tapetosomes possessing oleosins and triacylglycerols (TAGs), and the elaioplasts having unique polypeptides and neutral esters. B. campestris, for its simplicity of possessing only the AA genome and one predominant oleosin of 45 kDa, was studied. In the developing anthers, the lipids and proteins of the tapetosomes and elaioplasts were concomitantly accumulated but selectively degraded or retained. Upon incubation of isolated tapetosomes in a pH-5 medium, the predominant 45 kDa oleosin underwent selective enzymatic proteolysis to a 37 kDa fragment, which was not further hydrolyzed upon prolonged incubation. The unreacted 45 kDa oleosin was retained in the organelles, whereas the 37 kDa fragment was released to the exterior. The fragment would become the predominant 37 kDa polypeptide in the pollen coat. Isolated tapetosomes did not undergo hydrolysis of the TAGs upon incubation in media of diverse pHs. An alkaline lipase in the soluble fraction of the anther extract was presumed to be the enzyme that would hydrolyze the tapetosome TAGs, which disappeared in the anthers during development. The tapetum elaioplasts contained several unique polypeptides of 31-36 kDa. The gene encoding a 32 kDa polypeptide was cloned, and its deduced amino acid sequence was homologous to those of two proteins known to be present on the surface of fibrils in chromoplasts. Upon incubation of isolated elaioplasts in media of diverse pHs, the organelle polypeptides were degraded completely and most rapidly at pH 5, whereas the neutral esters remained unchanged; these neutral esters would become the major lipid components of the pollen coat. The findings show that the constituents of the two major tapetum organelles underwent very different paths of degradation, or modification, and transfer to the pollen surface.

Concentrations of persistent lipophilic compounds in fish are determined by exchange across the gills, not through the food chain

Uptake of persistent lipophilic toxicants in fish occurs via the food and by transfer across the body surface, notably the gills. Flux rates of most lipid soluble toxicants across the gills is rapid and the animal must eat at very high rates for feeding to have a significant effect on toxicant concentration in the body. The relative rates of uptake via feeding and transfer across the gills are analyzed from a theoretical and experimental standpoint. At the low feeding rates typical of fish, the uptake of toxicants in the food can be ignored when estimating toxicant body concentration.

The pilH gene encodes an ABC transporter homologue required for type IV pilus biogenesis and social gliding motility in Myxococcus xanthus

Type IV pilus genes have been shown to be required for social gliding motility in Myxococcus xanthus. We report the discovery of four additional pil genes: pilD, a homologue of type IV prepilin leader peptidases; and pilG, pilH and pilI, which have no known homologues in other type IV pilus systems. pilH encodes an ATP-binding cassette (ABC) transporter homologue, the first such homologue to be required for the biogenesis of any bacterial pilus type. pilG and pilI are co-transcribed with pilH and appear to be functionally related to pilH. Null mutants of pilG, pilH and pilI all lack social motility, are deficient in pilus production, have elevated sporulation efficiencies and display similar developmental abnormalities. In addition, all three mutations reduced the amount of PilA found in the supernatant after cells were sedimented from liquid culture. We suggest that the products of these three genes form a single ABC exporter complex, in which pilI is an integral membrane protein with membrane-spanning domains, and pilG is an accessory factor. The complex may participate in pilus assembly and/or the export of PilA pilin.

Contact stimulation of Tgl and type IV pili in Myxococcus xanthus

Myxococcus xanthus tgl mutants lack social motility and type IV pili but can be transiently stimulated to swarm and to make pili by contacting tgl+ cells. The absence of pili in tgl mutants is shown not to be due to the absence of pilin. The rate of pilus elongation after Tgl stimulation is shown to be similar to the rate of pilus elongation in wild-type cells, using a new more rapid assay for stimulation.

A PC-based surgical simulator for laparoscopic surgery

Surgical simulators for minimally invasive surgery have been developing in the 1990s. Most of them use high-end UNIX workstations for real-time simulation of complex human organ models. Only few of them have input devices with force feedback. Recently, personal computer technologies have made real-time display of relatively complex models feasible. We are developing an Intel-based laparoscopic surgical simulator that provides near real-time intuitive interaction between the trainee and simulated models of human organs. The surgical simulator has a prototypical scenario of cholecystectomic surgery. It can interactively simulate the deformation and cutting of cystic duct and vein. In addition, a set of input devices with force feedback has been designed and tested to imitate the manipulation of surgical instruments. The input device has five degrees of freedom and three of them are driven by DC motors to produce force feedback.

Regulation of expression of the pilA gene in Myxococcus xanthus

Type IV pili are required for social gliding motility in Myxococcus xanthus. In this work, the expression of pilin (the pilA gene product) during vegetative growth and fruiting-body development was examined. A polyclonal antibody against the pilA gene product (prepilin) was prepared, along with a pilA-lacZ fusion, and was used to assay expression of pilA in M. xanthus in different mutant backgrounds. pilA expression required the response regulator pilR but was negatively regulated by the putative sensor kinase pilS. pilA expression did not require pilB, pilC, or pilT. pilA was also autoregulated; a mutation which altered an invariant glutamate five residues from the presumed prepilin processing site eliminated this autoregulation, as did a deletion of the pilA gene. Primer extension and S1 nuclease analysis identified a sigma54 promoter upstream of pilA, consistent with the homology of pilR to the NtrC family of response regulators. Expression of pilA was found to be developmentally regulated; however, the timing of this expression pattern was not entirely dependent on pilS or pilR. Finally, pilA expression was induced by high nutrient concentrations, an effect that was also not dependent on pilS or pilR.

Isolation and characterization of neutral-lipid-containing organelles and globuli-filled plastids from Brassica napus tapetum

The monolayer tapetum cells of the maturing flowers of Brassica napus contain abundant subcellular globuli-filled plastids and special lipid particles, both enriched with lipids that are supposed to be discharged and deposited onto the surface of adjacent maturing pollen. We separated the two organelles by flotation density gradient centrifugation and identified them by electron microscopy. The globuli-filled plastids had a morphology similar to those described in other plant species and tissues. They had an equilibrium density of 1.02 g/cm(3) and contained neutral esters and unique polypeptides. The lipid particles contained patches of osmiophilic materials situated among densely packed vesicles and did not have an enclosing membrane. They exhibited osmotic properties, presumably exerted by the individual vesicles. They had an equilibrium density of 1.05 g/cm(3) and possessed triacylglycerols and unique polypeptides. Several of these polypeptides were identified, by their N-terminal sequences or antibody cross-reactivity, as oleosins, proteins known to be associated with seed storage oil bodies. The morphological and biochemical characteristics of the lipid particles indicate that they are novel organelles in eukaryotes that have not been previously isolated and studied. After lysis of the tapetum cells at a late stage of floral development, only the major plastid neutral ester was recovered, whereas the other abundant lipids and proteins of the two tapetum organelles were present in fragmented forms or absent on the pollen surface.

Eosinophilic ileitis with perforation caused by Angiostrongylus (Parastrongylus) costaricensis. A case study and review

Angiostrongylus costaricensis (classified under the more specific genus Parastrongylus by different authors) is a filiform intestinal nematode endemic to Central and South America, which afflicts primarily the pediatric population 1 to 13 years of age. Only three cases of adult infections have been previously documented outside the endemic region. To our knowledge, we report the first such case in the western United States, as well as the oldest patient yet recorded. Our patient is a 73-year-old woman living in Los Angeles who presented with an acute abdomen 4 weeks following a 5-month visit to El Salvador. Examination of the gross ileum removed at exploratory laparotomy revealed a perforation associated with a segmentally thickened intestinal wall. Microscopic examination showed eosinophilic ileitis, arterial lumens containing nematodes morphologically consistent with A costaricensis, eggs in the submucosa, and arteriolitis with thrombosis.

The Myxococcus xanthus pilT locus is required for social gliding motility although pili are still produced

Social gliding motility in Myxococcus xanthus depends on the presence of Type IV pili. To begin to examine the role of pili in social motility, 17 mutants were identified which had lost social motility, but still expressed pili. Four of these mutants carry point mutations which mapped to a locus upstream of the recently identified pilS, pilR, and pilA genes. Sequencing of this locus revealed a gene with homology to pilT from Pseudomonas Aeruginosa. Sequencing of the four point mutations revealed that they occurred within the M. xanthus pilT locus. A markerless deletion within M. xanthus pilT, similar to the four point mutations, disrupted social gliding behaviour but did not interfere with pilus formation or pilus-dependent cell-cell agglutination. Using time-lapse videomicroscopy, residual social motility was observed in dsp- strains (known to be deficient in fibril but not pilus production); this was not observed in a delta pilT dep- double mutant. Two genes flanking pilT were also sequenced, and found to have homology to pilB and pilC from P. aeruginosa. Markerless deletions within these genes caused both pilus and social-motility defects. These results indicate that M. xanthus pilB and pilC are required for pilus biogenesis, while pilT is required for assembled pili to play their role in social motility. Thus, pilB, pilT, pilC, pilS, pilR and pilA form a contiguous cluster of pil genes required for social motility.

[Endoscopic diagnosis and clinical experience of colonic tuberculosis]

From February 1979 to May 1994, 18 cases of colonic tuberculosis were detected by colonscopy at Chang Gung Momorial Hospital, Linkou Medical Center. There were 10 males and 8 females, with mean age of 43.6. In ten, the diagnosis was confirmed histologically or bacteriologically in colonic biopsy material and post-operated lymph nodes. The remaining 8 patients was suspected on colonoscopy, and had good response to antituberculous therapy. The major symptoms were abdominal pain (83%), diarrhea (67%), and body weight loss (61%). Average duration from symptoms to diagnosis was 4.1 months. Chest X-ray revealed active pulmonary tuberculosis in 14 of 18 patients (78%), 4 of 14 patients were military type. The colonic tuberculosis involved in ileocecal area in 6, ileocecum and contiguous colonic regions in 7, segmental colonic involvement in 4, and pancolitis in 1 patient. Multiple ulceration and ulcerohypertrophic lesions were the major colonoscopic findings. Typical caseating granuloma were found in 5 cases (36%) from colonoscopic biopsy, the other 5 from surgical resected specimens. Antituberculous therapy produced remarkable symptomatic improvement in all patients except 2 cases complicated with intestinal obstruction necessitating laparotomy. Colonoscopy with biopsy is a useful diagnostic tool in early diagnosis and avoiding unnecessary laparotomy in colonic tuberculosis.

Markerless deletions of pil genes in Myxococcus xanthus generated by counterselection with the Bacillus subtilis sacB gene

In-frame deletions of pilA and pilS were constructed in Myxococcus xanthus with a plasmid integration-excision strategy facilitated by sacB. sacB conferred sucrose sensitivity upon its M. xanthus host only when it lay in the same orientation as adjacent M. xanthus genes. Gene orientation also affected the efficiency of sucrose counterselection in the sucrose-sensitive strains. The deltapilA mutant lacked pili and social motility, while the deltapilS mutant showed no defect in either phenotype.

Management of rigid post-traumatic kyphosis

STUDY DESIGN

Rigid post-traumatic kyphosis after fracture of the thoracolumbar and lumbar spine represents a failure of initial management of the injury. Kyphosis moves the center of gravity anterior. The kyphosis and instability may result in pain, deformity, and increased neurologic deficits. Management for symptomatic post-traumatic kyphosis always has presented a challenge to orthopedic surgeons.

OBJECTIVES

To evaluate the surgical results of one stage posterior correction for rigid symptomatic post-traumatic kyphosis of the thoracolumbar and lumbar spine.

SUMMARY OF BACKGROUND DATA

The management for post-traumatic kyphosis remains controversial. Anterior, posterior, or combined anterior and posterior procedures have been advocated by different authors and show various degrees of success.

METHODS

One vertebra immediately above and below the level of the deformity was instrumented posteriorly by a transpedicular system (internal fixator AO). Posterior decompression was performed by excision of the spinal process and bilateral laminectomy. With the deformed vertebra through the pedicle, the vertebral body carefully is removed around the pedicle level, approximating a wedge shape. The extent to which the deformed vertebral body should be removed is determined by the attempted correction. Correction of the deformity is achieved by manipulation of the operating table and compression of the adjacent Schanz screws above and below the lesion.

RESULTS

Thirteen patients with post-traumatic kyphosis with symptoms of fatigue and pain caused by slow progression of kyphotic deformities received posterior decompression, correction, and stabilization as a definitive treatment. The precorrection kyphosis ranged from 30-60 degrees, with a mean of 40 degrees +/- 10.8 degrees. After correction, kyphosis was reduced to an average of 1.5 degrees +/- 3.8 degrees, with a range from -5 degrees to 5 degrees. The average angle of correction was 38.8 degrees +/- 10.4 degrees, with a range from 25 degrees to 60 degrees. Significant difference was found between pre- and post-operative kyphosis measures (P < 0.001). The follow-up period for all patients was 2 years, and the average kyphosis angle measured at the moment was 3.8 degrees +/- 3 degrees with a range from -3 degrees to 8 degrees. Substantial overall improvement was achieved in the 13 patients.

CONCLUSION

This method provides single-stage posterior decompression, correction, and stabilization on as definitive management for post traumatic kyphosis of the thoracolumbar and lumbar spine.

Ultrasound-guided percutaneous transhepatic fine needle aspiration cytology study of gallbladder polypoid lesions

OBJECTIVE

To determine the accuracy and safety of ultrasound (US)-guided percutaneous transhepatic fine needle aspiration cytology (PT FNAC) in the diagnosis of large gallbladder (GB) polyps, especially cholesterol polyps.

METHODS

Between January 1993 and April 1995, 17 patients with GB polyps of a size over 1 cm were examined preoperatively with US-guided PT FNAC, with needle aspiration from the center of the polyps. A cytological-histopathological correlation study was performed postoperatively to assess the accuracy of the PT FNAC results.

RESULTS

1) All eight cholesterol polyps were accurately diagnosed with the PT FNAC alone, showing foamy histiocytes. 2) In five patients, a diagnosis of epithelial tumor was made with PT FNAC study, showing the presence of columnar epithelium, but the PT FNAC failed to detect focal malignant change in adenomas of three of these patients. Only one case of adenocarcinoma was correctly diagnosed preoperatively by the PT FNAC. 3) The PT FNAC failed to detect an inflammatory polyp in one patient. 4) Failed cytology study was encountered in three patients-only bile was aspirated out. One patient had a GB stone, misdiagnosed as a GB polyp, another had an adenomyoma, and the last patient had chronic cholecystitis with Rokitansky-Aschoff sinuses. 5) One complication occurred-mild bile peritonitis.

CONCLUSIONS

US-guided PT FNAC directly targeting the GB lesions seems accurate in the diagnosis of cholesterol polyps, and is a safe procedure.

Physical disability among American medical students

The present survey aimed to assess the prevalence and nature of physical disabilities among medical school graduates and to investigate the academic performance of these new physicians with disabilities. A questionnaire was sent to the deans of student affairs of each of the then existing 128 United States and Puerto Rican medical schools, addressing the profiles of students with physical disabilities in the 1987 through 1990 graduating classes. Seventy-seven (60%) United States and Puerto Rican medical schools responded to the questionnaire, of which 67 were able to complete it. A total of 67 students with physical disabilities (40 males and 27 females) were reported. Three of the 67 students were excluded from the study because their conditions did not match our definition of physical disability. The remaining 64 students (38 males and 26 females), ranging from 0 to 10 per school, comprised 0.19% of the 33,138 students who graduated from the 67 medical schools during these 4 academic yr. The disabilities represented by the 64 students encompassed a wide spectrum of etiologies, including neurologic (39%), musculoskeletal (20%), medical-surgical (13%), visual (13%), and auditory (9%) problems. The majority of students with disabilities had above average (36%) to average (48%) academic standings. The actual prevalence of medical students with disabilities might be higher than reported because of the underreporting of the less noticeable types of disabilities.

Azygos blood flow in cirrhosis: measurement with MR imaging and correlation with variceal hemorrhage

PURPOSE

To evaluate magnetic resonance (MR) measurement of azygos blood flow (ABF) in assessment of risk of variceal hemorrhage in cirrhosis.

MATERIALS AND METHODS

ABF in 50 patients with cirrhosis and 20 healthy control subjects was evaluated with phase-contrast cine MR imaging at the transaxial subcarinal plane. Group 1 included nine patients with cervical-drainage varices draining into brachiocephalic vein; group 2 included 41 patients with varices draining into azygos vein and was subdivided as group 2A, 15 patients with variceal hemorrhage, and group 2B, 26 without variceal hemorrhage.

RESULTS

Azygos flow rate and velocity were increased in patients compared with that in control subjects. ABF in group 2A was faster than that in group 2B (cutoff, 15 cm/sec; sensitivity, 80%; specificity, 89%). Group 1 had ABF close to that of group 2B, but variceal hemorrhage occurred in seven of nine patients in group 1 versus 15 of 41 patients in group 2 (78% vs 37%; P = .029).

CONCLUSION

Patients with cirrhosis with cervical-drainage varices or ABF greater than 15 cm/sec may have higher risk for variceal hemorrhage.

Genetic and functional evidence that Type IV pili are required for social gliding motility in Myxococcus xanthus

The social gliding behaviour of Myxococcus xanthus has previously been associated with the presence of polar pili. A Tn5 transposon insertion was isolated which introduces a defect in social gliding and is genetically linked to a known sgl locus; this insertion was found also to cause a piliation defect. A 2.7 kb section of DNA was isolated from either side of this transposon and sequenced, revealing three genes which encode amino acid sequences with substantial similarity to components of the Type IV pilus biogenesis pathway in Pseudomonas aeruginosa. The myxococcal pilA gene encodes a putative pilin precursor with a short signal sequence and processing site similar to those of other Type IV pilins. Myxococcal pilS and pilR encode amino acid sequences with similarity to PilS and PilR of P. aeruginosa, as well as to other members of the NtrB/C family of two-component regulators. Mutations within pilR and pilA that have no polar effect were demonstrated to be responsible for pilus and social motility defects. These results indicate that the pili of M. xanthus belong to the Type IV family of pili, and demonstrate that these pili are actually required for social motility.

Effect of schisandrin B on hepatic glutathione antioxidant system in mice: protection against carbon tetrachloride toxicity

Pretreating female Balb/c mice with schisandrin B (Sch B) at increasing daily doses (1-4 mmol/kg) for 3 days caused dose-dependent increases in hepatic glutathione S-transferase (GST) and glutathione reductase (GRD) activities. However, the activities of glucose-6-phosphate dehydrogenase (G6PDH), Se-glutathione peroxidase (GPX), and gamma-glutamylcysteine synthetase (GCS) were down-regulated to varying degrees in a dose-dependent manner. While there were biphasic changes in hepatic reduced glutathione (GSH) level as well as susceptibility of hepatic tissue homogenates to in vitro peroxide-induced GSH depletion, a gradual decrease in hepatic malondialdehyde content was observed. The beneficial effect of Sch B on the hepatic GSH anti-oxidant system became more evident after CCl4 challenge. The same Sch B pretreatment regimen caused a dose-dependent protection against carbon tetrachloride (CCl4)-induced hepatotoxicity. The hepatoprotection was associated with significant enhancement in hepatic GSH status, as indicated by the substantial increase in tissue GSH levels and the corresponding decrease in susceptibility of tissue homogenates to GSH depletion. Where the activities of GST and GRD were increased linearly over non-CCl4 control values, there was also a gradual elevation in G6PDH activity upon administration of increasing doses of Sch B. In contrast, GPX activity was moderately down-regulated. The ensemble of results suggests that the hepatoprotection afforded by Sch B pretreatment may mainly be attributed to the enhancement in the functioning of the hepatic GSH anti-oxidant system, possibly through stimulating the activities of GSH related enzymes.