Effect of Carbon Black on the J-Integral and Strain Energy in the Crack Tip Region in a Vulcanized Natural Rubber

1) The J-integral is path independent in both PS and SEN specimens and equals the tearing energy. 2) The critical J-integral at initiation is less in PS specimens than in SEN specimens, because the greater biaxial stress in PS restricts the process zone. 3) At initiation, the crack-tip radius, proportional to the local strain, is independent of CB. 4) The energy density within and the size of the process zone near the crack tip increase with CB; these are major contributions to CB reinforcement.

[Alteration of plasma amino acid content in primary liver cancer patients]

Twenty-two plasma free amino acid contents from 22 primary liver cancer (PLC) patients were assayed by means of HPLC and compared with those from 16 normal subjects. The results showed that in PLC patients, plasma total amino acid (TAA), branched chain amino acid (BCAA), glycogenic amino acid, glutamine, histidine and arginine were lowered, while plasma aromatic amino acid (AAA) and methionine did not decrease significantly resulting in the BCAA/AAA ratio decline. Comparing 8/22 subclinical and 14/22 clinical liver cancers with healthy controls respectively, it was found that there was a decrease of plasma TAA, glutamine, arginine, histidine, BCAA and BCAA/AAA ratio, and an increase of tyrosine, in subclinical stage of PLC. It suggests that alteration of most amino acids occur in the early stage of PLC and become more obvious in the moderate and late stages. The changes of plasma amino acid contents in PLC were different from those in chronic liver diseases. The alteration of plasma amino acid contents in subclinical stage of PLC suggests that the disturbance of amino acid metabolism be resulted from malignancy. Correction of the amino acid metabolic disturbance in PLC patients may enhance the inhibition of tumor growth and improve the host metabolism and anti-cancer effect.

Localization of antigen-specific lymphocytes following lymph node challenge

The effect of subcutaneous injections of Brucella abortus strain 19 antigen on the specific localization of autologous lymphocytes in the regional nodes of calves was analysed by fluorescent labelling and flow cytometry. Both in vitro and in vivo FITC labelling of lymphocytes indicated the preferential migration of lymphocytes from a previously challenged lymph node to a recently challenged lymph node. However, lymphocytes from a lymph node challenged with B. abortus failed to localize preferentially in a lymph node challenged with a control antigen, Listeria monocytogenes. Lymph node cells, enriched for T lymphocytes and isolated from primary stimulated or secondary challenged B. abortus lymph nodes, could proliferate when cultured with autologous antigen-pulsed macrophages. The kinetics of [3H]thymidine incorporation in lymphocytes from secondarily challenged lymph nodes occurred earlier and to a greater extent when compared with lymphocytes from primary challenged lymph nodes. Our data show that the accumulation of B. abortus-specific lymphocytes in secondarily challenged lymph nodes is increased by the presence of the specific antigen.

The induction of meningeal inflammation by components of the pneumococcal cell wall

Pneumococcal cell wall induces meningeal inflammation in rabbits injected intracisternally with greater than 10(5) cell equivalents. Both of the major cell wall components, teichoic acid and peptidoglycan, contribute to this inflammatory activity although responses differ depending on the chemical nature, size, and complexity of these fractions. Challenge with teichoic acid (membrane or wall associated) results in greater inflammation at 5 hr than at 24 hr. Degraded teichoic acid is inactive. In contrast, the inflammation caused by whole cell wall or high-molecular-weight peptidoglycan-containing fractions increases in intensity from 5 to 24 hr. Peptidoglycan fractions lose activity at 24 hr when hydrolyzed to disaccharide-stem peptide moieties. Generation of free cell wall components in cerebrospinal fluid as, for example, during treatment with antibiotics that are bacteriolytic as well as bactericidal, could contribute to increased inflammation in the subarachnoid space.

Retinal changes in myotonic dystrophy: a clinicomorphological study

This report appears to be the first ultrastructural study of the maculopathy and peripheral pigmentary retinopathy in myotonic dystrophy. Nine eyes from five patients observed during life are described. The findings were similar in all eyes, the retinal pigment epithelium in the macular region containing an accumulation of lipofuscin in large hyperpigmented cells. Pigment-laden profiles found in the subpigment epithelial space or subretinal space were interpreted as an attempt to discharge the pigment. Stress fibres of actin microfilaments were thrown into prominence by the irregularity of the pigment epithelium. In the periphery migration of retinal pigment cells into the retina occasionally resulted in the formation of bone corpuscles around occluded vessels, as occurs in retinitis pigmentosa; but more often the clumps were coarser and surrounded basement membrane material. Central and peripheral epiretinal membranes were also observed.

Repositioning of Descemet's membrane: a case report

An 80-year-old Australian was admitted to Concord Hospital for right cataract extraction and intraocular implant. During the procedure under local anaesthesia, two-thirds of Descemet's membrane was stripped down into the anterior chamber. The membrane was later repositioned by air injection into the anterior chamber. Sixteen months later, her right visual acuity is 6/9 and she reads the newspapers.

Objective pathological diagnosis of coal worker's pneumoconiosis

Pertinent pathological features of lungs obtained at autopsies from 99 coal miners were compared with those observed in the lungs of 268 male town dwellers of comparable age who were not occupationally related to the coal mining or other industries at risk for development of pneumoconiosis. The degree of anthracotic pigment deposition and severity of type of pigmented lesion with its accompanying reticulum fiber formation and fibrosis were significantly greater in lungs of miners. There was a high degree of overlap in degree of pigment deposition, particularly those quantitated as grades 1 and 2 and in lesions regarded as types 1 and 2. The greatest divergence was observed for prevalence of nodular pulmonary lesions (type 4). There was also a considerable divergence in the type 3 alteration characterized by nonnodular aggregates of carbon-laden macrophages accompanied by minimal reactive fibrosis. It appears that an objective pathological diagnosis of coal workers' pneumoconiosis (CWP) can be rendered only by the demonstration of type 4 lesions. Approximately 25% of coal miners exhibited unequivocal features of CWP. No significant differences concerning incidence or types of emphysema or frequency of chronic cor pulmonale were encountered between the two populations.