Generation of splenic follicular structure and B cell movement in tumor necrosis factor-deficient mice

Secondary lymphoid tissue organogenesis requires tumor necrosis factor (TNF) and lymphotoxin alpha (LTalpha). The role of TNF in B cell positioning and formation of follicular structure was studied by comparing the location of newly produced naive recirculating and antigen-stimulated B cells in TNF-/- and TNF/LTalpha-/- mice. By creating radiation bone marrow chimeras from wild-type and TNF-/- mice, formation of normal splenic B cell follicles was shown to depend on TNF production by radiation-sensitive cells of hemopoietic origin. Reciprocal adoptive transfers of mature B cells between wild-type and knockout mice indicated that normal follicular tropism of recirculating naive B cells occurs independently of TNF derived from the recipient spleen. Moreover, soluble TNF receptor-IgG fusion protein administered in vivo failed to prevent B cell localization to the follicle or the germinal center reaction. Normal T zone tropism was observed when antigen-stimulated B cells were transferred into TNF-/- recipients, but not into TNF/LTalpha-/- recipients. This result appeared to account for the defect in isotype switching observed in intact TNF/LTalpha-/- mice because TNF/LTalpha-/- B cells, when stimulated in vitro, switched isotypes normally. Thus, TNF is necessary for creating the permissive environment for B cell movement and function, but is not itself responsible for these processes.     

A probabilistic structure life prediction system for container ship repair and inspection

A probabilistic fracture mechanics code has been developed to assess the impact of welding procedure, inspection frequency, and flaw detection/rejection criteria, on the reliability of butt weld joints in container ship deck doubler plates. A fatigue loading stress spectrum was developed based on statistical sea state data and a structural model of a ship. An initial flaw size distribution was developed from ultrasonic inspection results of deck doubler butt welds. Other random variables included fracture toughness and inspection detection of weld defects. Probability distributions of the input random variables were applied through Monte Carlo simulation to a deterministic fracture mechanics model for fatigue crack growth. This paper describes the development and application of the analysis program.     

Seed extract of Aeginetia indica L induces cytokine production and lymphocyte proliferation in vitro

The development of the human medial superior olivary nucleus was studied in serial sections of 10 fetuses at 12-35 weeks of gestation (WG), an infant at 2 months of age and an adult of 63 years using an electronic planimeter with a computer. Morphometric analysis suggested that the development of the human medial superior olivary nucleus accelerates between 16 and 21 WG in terms of columnar lengths and volumes, neuronal sizes and circularity ratios, while it matures gradually in terms of the amount of Nissl bodies.     

Investigation of limbal touch sensitivity using a Cochet-Bonnet aesthesiometer

Using the hypertensive gas technique, before touching the melanoma eye for enucleation intraocular pressure is raised to maximum by an intravitreal gas injection (average 1.2 ml of perfluorocarbon or air), resulting in a rock-hard eye. Changes in intraocular pressure are no longer possible, since the hard eye condition and avascularity persist during enucleation. The vortex veins appear collapsed. Before cutting the optic nerve and vessels, they are compressed by a broad hemostatic clamp for three minutes and then severed by a blade located in the middle of the clamp. With the hypertensive gas technique there is neither bleeding of vortex veins nor of proximal end of stump, which continues to be compressed by the hemostatic clamp. Fifteen patients with choroidal melanomas were enrolled in a prospective study with the hypertensive gas technique from 9/1987 to 6/1989; prior radiotherapy was not performed. Average base diameter of melanoma measured 13.2 mm, height 8.4 mm. Cytology was: 11x spindle, 3x mixed, 1x epitheloid cells. At reexamination in 7/1991 (average follow-up 2.75 years), 2 diabetics had died with no detectable metastases, and 1 of the 15 melanoma patients (6.7%) had died with metastases 2 years after enucleation. The hypertensive gas technique does not postpone enucleation of a melanoma eye while presumed prophylaxis is administered, does not require additional instruments, and takes only a minute when the eye is already draped for surgery. The firm and avascular globe facilities a faster removal of the melanoma eye with practically no bleeding from the bulb.     

Low maternal serum levels of pregnancy associated plasma protein A (PAPP-A) in the first trimester in association with abnormal fetal karyotype

OBJECTIVE: To assess the relation between maternal serum pregnancy associated plasma protein A (PAPP-A) in the first trimester and the outcome of pregnancy by karyotype. DESIGN: A retrospective study of PAPP-A levels in blood samples collected prior to chorionic villus sampling. SETTING: Milan, Italy. SUBJECTS: Five hundred twenty-two women aged 20 to 47, at 7 to 11 weeks gestation, prior to undergoing chorionic villus sampling. Four hundred forty-five women had a pregnancy with a normal karyotype; in 30 pregnancies the karyotype was abnormal (including 14 cases of Down's syndrome and 7 of trisomy 18). MAIN OUTCOME MEASURES: Normal or abnormal fetal karyotype. Serum PAPP-A at 6 to 11 weeks gestation measured by radioimmunoassay. RESULTS: The median value of PAPP-A in the abnormal group was 0.27 multiples of the normal median (MoM). This is significantly lower than the median value in the normal group (1.01 MoM) (95% CI for the difference 0.46-0.84 MoM; P < 0.00001 Mann-Whitney test). CONCLUSIONS: There is an association between low levels of PAPP-A in the first trimester with chromosome anomalies. Screening by measurement of PAPP-A might detect 60% of cases of Down's syndrome in the first trimester with a false positive rate of 5%.     

Hepatitis delta virus antigen forms dimers and multimeric complexes in vivo

Although the hepatitis delta virus genome contains multiple open reading frames, only one of these reading frames is known to be expressed during replication of the virus. This open reading frame encodes two distinct molecular species of hepatitis delta antigen (HDAg), p24 delta and p27 delta, depending on the location of the stop codon which terminates translation. We found antibody specific for p27 delta to be capable of precipitating p24 delta in extracts of infected liver, indicating that p27 delta and p24 delta form heterologous complexes in vivo. After cross-linking with 0.05% glutaraldehyde, specific HDAg dimers were detected in antigen prepared from both the liver and serum of an HDV-infected woodchuck carrier of woodchuck hepatitis virus. Guanidine HCl-denatured HDAg extracted from liver and dialyzed against phosphate-buffered saline sedimented in rate-zonal sucrose density gradients as 15S multimeric complexes. These 15S multimers were stable in the presence of 1.2% Nonidet P-40. After RNase digestion, the 15S complex was reduced to a 12S complex without associated RNA, while boiling for 3 min in 1% sodium dodecyl sulfate-0.5% 2-mercaptoethanol further reduced the 15S complex to 3S HDAg monomers. In the absence of glutaraldehyde cross-linking, HDAg extracted from liver migrated as monomer species in reducing and nonreducing gels, suggesting that the conserved cysteine residue present in p27 delta does not play a role in the formation of either dimers or multimers. On the other hand, an amino-terminal chymotrypsin-digested HDAg fragment, with a predicted length of 81 or less amino acids, retained the ability to form dimers, consistent with the hypothesis that a coiled-coil motif present between residues 27 and 58 may play a role in HDAg protein interactions in vivo.     

Flatpea intoxication in sheep and indications of ruminal adaptation

Of 36 patients with facial nerve palsy caused by the fracture of the temporal bone, 28 were treated surgically and 8 conservatively. The way of treatment was determined after the detailed radiologic, neurootologic, vestibular and functional hearing examinations as well as of the damaged facial nerve. Numerous neurootologic disorders have the decisive clinical value in evaluation of the site and degree of destruction and selection of adequate way of treatment. The authors have shown that early surgical intervention and combined transmastoid and translabyrinthine approach provide the most suitable conditions for surgical management of the facial nerve and all associated damages in the region of the middle and inner ear.     

Plasmodium-falciparum-infected erythrocytes adhere to immortalized human bone marrow endothelial cells

Two cases of recurrent pancreatitis, due to duodenal duplication, are reported. The aim of this paper is to emphasise the role of endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC) in the detection of associated pancreaticobiliary anomalies and in the planning of the correct surgical approach. The order of imaging in a child with recurrent pancreatitis should be US, barium meal and PTC. ERCP is often difficult to perform in children.