Role of the B cell antigen receptor in antigen processing and presentation. Involvement of the transmembrane region in intracellular trafficking of receptor/ligand complexes

To study the role of the B cell Ag receptor (membrane-bound Ig [mIg]) in Ag processing and presentation, we have generated several Ig transfectants that express transfected TEPC-15 idiotype (T15-Id) mIgM with phosphorylcholine (PC)-binding specificity. The wild-type Ig transfectant is able to present a specific Ag (e.g., PC-conjugated hen egg-white lysozyme [PC-HEL]) more efficiently than a nonspecific Ag (HEL) to a T cell hybridoma recognizing an epitope on the HEL molecule. A substitution in the entire spacer, transmembrane, and cytoplasmic region of mIg with an equivalent region of I-A alpha chain completely abolishes this mIg-enhanced Ag presentation. Experiments with the wild-type and substituted variant Ig transfectants suggest that this substitution may interfere with normal intracellular trafficking of mIg after cross-linking with specific Ag or antibodies specific for the mIg (anti-T15-Id mAb). Prolonged treatment of the wild-type Ig transfectants with specific Ag or anti-T15-Id mAb reduces the surface expression of T15-Id mIgM and leads to an accumulation of T15-Id mIgM inside the cells. The reduced surface expression and the elevated cytoplasmic accumulation of T15-Id mIgM are not observed in the variant Ig transfectant. Despite the ability of the variant to endocytose ligands similarly to the wild-type Ig transfectant, this variant displays a higher rate of recycling of the mIg/ligand complexes back to the cell surface and a lower rate of degradation of the ligands. These abnormalities may be responsible for the deficiency in mIg-mediated enhancement of Ag presentation in the variant Ig transfectant. Therefore, our results suggest that the transmembrane region of mIg is involved in intracellular trafficking of receptor/ligand complexes and that proper delivery and handling of internalized Ag are required for the enhanced presentation of specific Ag by B cells.     

The effect of the vole subspecies of the plague microbe on the viability of Callopsylla caspia fleas]

When infected with cultures of plague microbe reared at 28 C the experimental fleas showed no reliable differences in the mortality as compared to control ones. By contrast, the infection with agent cultures reared at 37 C as well as the infection on agonizing white mice caused a statistically reliable increase in the mortality in insects of both sexes. In the groups of fleas infected on white mice the most intensive mortality was observed during the first 24 hours after the infectious feeding that, apparently, is connected with the effect of toxins present in the blood of agonizing animals.     

Mast cell involvement in the rat paw oedema response to 1,8-cineole, the main constituent of eucalyptus and rosemary oils

The present studies tested the ability of 1,8-cineole to produce inflammatory oedema in the hind paw of the rat and verified the possible involvement of mast cells in the response. Subplantar injection of 1,8-cineole (10, 15 and 20 microl/paw) induced a dose-dependent paw oedema which was apparent within 30 min. At higher doses the oedema effect was persistent, peaked at 2 h, and then decreased gradually but was still pronounced at 24 h post injection. In contrast, the oedema produced by mast cell degranulator compound 48/80 (10 microg/paw) had a rapid onset with a peak effect at the first hour, followed by a gradual decrease thereafter and at 24 h post injection it was almost absent. The oedema response to 20 microl 1,8-cineole was significantly inhibited throughout its time-course in rats pretreated with antihistaminic and antiserotonergic drugs such as diphenhydramine, methysergide and cyproheptadine or with ketotifen, a mast cell stabilizer. A more effective blockade of the oedema response was, however, observed in rats depleted of mast cell granules by systemic treatment with compound 48/80. Furthermore, 1,8-cineole was able to cause rat peritoneal mast cell degranulation (94%) in vitro, in a concentration as low as 0.3 microl/ml, which was almost comparable to that produced by 0.1 microg/ml of compound 48/80. The data provide evidence of a key role for the mast cell in 1,8-cineole-induced hind paw oedema in the rat.     

Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia

Some children with Chiari malformation and achondroplasia require posterior fossa decompression that typically includes expansion of the dural tube with duraplasty. Infants and young children, however, may have a more distensible dura mater than do older patients. Furthermore, the structures that compress the hindbrain of young patients may be the bone and abnormally thickened atlantooccipital membrane, i.e., dural band, rather than the dura mater. We have treated 7 children who had Chiari malformation or achondroplasia with posterior fossa decompression without duraplasty. All children were symptomatic; 3 had Chiari-I malformations, 2 Chiari-II malformations, and 2 achondroplasia. The age range was 3 months to 2.5 years (mean 15.1 months). The exent of tonsillar herniation and other hindbrain anomalies was assessed on preoperative magnetic resonance imaging. The infants with Chiari-II malformations underwent cervical laminectomies, whereas the other young children with Chiari-I malformations or achondroplasia underwent suboccipital craniectomy as well as cervical laminectomy. In Chiari malformation, the dural band was divided; in achondroplasia, there was no identifiable dural band. Following bony decompression and division of the identifiable dural band, immediate expansion of the stenotic region with visible cerebrospinal fluid space posterior to the neural elements could be ascertained by intraoperative ultrasonography. During a follow-up period ranging from 4.5 months to 4 years (mean 22 months), all patients made improvements in their symptoms, 3 having complete resolution of their symptoms. This preliminary experience indicates that in children 2 years of age or younger, posterior fossa bony decompression without duraplasty can be effective treatment for Chiari malformations or achondroplasia.     

Control of apex shape of the fiber probe employed in photonscanning tunneling microscope by a multistep etching method

In this paper, we discuss about the control of the shape of the very apex of a sharpened fiber probe used in photon scanning tunneling microscope (PSTM) by means of a method based on selective chemical etching. Under ambient conditions, through a multistep etching method proposed here, fiber probes with a flattened apex having a diameter of around 15-20 nm could be produced with high reproducibility. It has also been discovered that, during the etching process, the shape of the apex of the probe takes a rounded or a flattened shape with respect to the etching time in an almost cyclic fashion and such a phenomenon could help in understanding the mechanism of the etching process. These kind of probes with flat apex after metal coating are suitable for the fabrication of apertured probes used in PSTM and also for super tips which have a promising future as nanosensors in the fields of biology and biochemistry     

Effect of delta ferrite content on the corrosion resistance of type 316 clad metals

Austenitic claddings of type 316 were obtained by SMAW (Shielded Metal Arc Welding) and SAW (Submerged Arc Welding) processes, using type 316 L electrodes on low carbon boiler steel (SA 515 Gr 60) with type 309 L as a barrier layer deposited by the SAW process. Welding heat input was changed in order to obtain different ferrite contents in the cladding. The clad samples were post-weld heat treated at 650°C for 50 and 200 h. The top layer of the cladding was removed and the specimens were then subjected to intergranular corrosion tests (ASTM A-262-75, practices A, B, C and E, viz. 10% oxalic acid electrolytic etch; ferric sulfate ?50% sulfuric acid; 65% nitric acid and copper-copper sulfate ?16% sulfuric acid tests) and controlled potential etching test. The study indicated that the ferrite content of the cladding decreases with increasing current. Ferrite transformed after PWHT (post weld heat treatment) was relatively more in claddings obtained with low heat input and containing high ferrite content in the as-clad condition. PWHT led to brittle fracture of high ferrite claddings (above 10 FN). The corrosion attack of ferrite was found to depend on environment. 65% nitric acid attacked ferrite preferentially, whereas in acid-ferric sulfate, ferrite was intact and austenite was attacked. No sample exhibited susceptibility to intergranular corrosion in the as-clad or PWHT conditions in the copper-copper sulfate ?16% acid test. However, PWHT specimens with low ferrite contents (3.55 FN) exhibited grain boundary precipitation at the interface of two adjacent layers. In general, ferrite was found to be beneficial in controlling corrosion rates of clad metals after PWHT. Heat input, within the range studied, did not affect the corrosion rates significantly.     

Effects of misoprostol on pentylenetetrazol-induced seizures in mice

The effects of prostaglandin E-analogue misoprostol on the susceptibility to pentilenetetrazol (PTZ)-induced seizures were examined in mice. Misoprostol (200-800 micrograms/kg), given subcutaneously 45 min before the subconvulsive dose of PTZ (30 mg/kg, i.p) provoked dose-dependent clonic-tonic seizures (30 to 100%) and mortality in mice. At 300 g/kg, s.c., misoprostol pretreatment significantly (p < 0.05) lowered the onset latency to first convulsion as well as the latency to mortality induced by a convulsive dose of PTZ (60 mg/kg, i.p.). At this dose misoprostol was found to lower the CD50 and Ld50 values for PTZ by 21% and 36% respectively. The results suggest that prostaglandins are likely to lower the threshold for convulsions.     

Treatment of stage I-IIA breast cancer of medial-central localization]

702 patients with breast cancer were followed-up after, sparing and radical operations combined with radiation and polychemotherapy. Of adjuvant treatments, radiation therapy showed to be more effective than chemotherapy. Methods of operative treatment combined with radiation are not essential in the treatment of early stages of breast cancer.