Effect of fatty acids on the accelerated sulfur vulcanization of rubber by active zinc/carboxylate complexes

The effect of fatty acids with different aliphatic chain lengths on the accelerated vulcanization reaction of isoprene rubber was investigated through the generation of new intermediates composed of dinuclear bridging bidentate zinc/carboxylate complexes. Using the combination of in situ time-resolved Fourier-transform infrared spectroscopy and in situ time-resolved zinc K-edge X-ray absorption fine structure spectroscopy, the essential complex structure of the intermediates formed during the vulcanization reaction of isoprene rubber was determined to be independent of the aliphatic chain length of fatty acids. However, the reactivity of arachidic acid with ZnO was found to be low, which prolonged the induction period and curing time, and slowed down the curing rate in the vulcanization of isoprene rubber. These results help to understand the complicated vulcanization reaction of rubber, especially natural rubber, which inherently contains various fatty acids. The results obtained in this study are important for developing well-designed high-performance natural rubber products in the future.

The effect of fatty acids with different aliphatic chain lengths on the accelerated vulcanization reaction of isoprene rubber was investigated through the generation of new intermediates composed of dinuclear bridging bidentate zinc/carboxylate complexes.     

Acquired Thrombotic Thrombocytopenic Purpura Following BNT162b2 mRNA Coronavirus Disease Vaccination in a Japanese Patient

A 57-year-old man without underlying diseases presented with fatigue, loss of appetite, and jaundice 1 week after receiving the first dose of the BNT162b2 mRNA coronavirus disease 2019 (COVID-19) vaccine and showed hemolytic anemia with fragmented erythrocytes and severe thrombocytopenia 2 weeks after receiving the vaccine. An a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) activity level of <10% and ADAMTS13 inhibitor positivity confirmed the diagnosis of acquired thrombotic thrombocytopenic purpura (TTP). Combination therapy with plasma exchange, corticosteroid, and rituximab improved the clinical outcome. We herein report the first Japanese case of TTP possibly associated with vaccination. Physicians should be alert for this rare but life-threatening hematological complication following COVID-19 vaccination.     

Muscular Metastasis of Hepatocellular Carcinoma: Case Report and Literature Review

There are few case reports of hepatocellular carcinoma (HCC) metastasis to the skeletal muscle. A 78-year-old man developed a mass in the right shoulder. Washout of contrast medium during contrast-enhanced ultrasonography (CEUS) in both the primary HCC and the metastatic site was detected. Several nodules were scattered throughout the liver on an autopsy. In addition, the moderately differentiated HCC had metastasized to the right teres major muscle. Rare muscular metastasis should be considered if a hepatic tumor is moderately or poorly differentiated HCC. Early washout during CEUS is consistent with a pathological diagnosis of moderately or poorly differentiated HCC.     

Microcirculatory changes in the development of the cerebrovascular adaptation]

Recently, long-term cerebrovascular adaptations after unilateral carotid ligation that increase the tolerance of the brain to subsequent episode of ischemia was reported(J Cereb Blood Flow Metab, 1998). However, the pathophysiological mechanisms underlying the phenomenon was unknown. We examined regional cerebral blood flow(rCBF) before, during and after subsequent ischemia in the development of the adaptation. Male Wistar rats(n = 18) were used. Unilateral(right) carotid artery ligation was performed 3 hours(group A: n = 8), 3 days(group B: n = 10) before forebrain ischemia. With bilateral carotid arteries occlusion, mean arterial blood pressure(MABP) was reduced by hypobaric hypotension down to 50 mmHg and maintained constant for 30 min. After hypotension, the experiment continued for 90 min. Local CBF were registered at 25(5 x 5) identical locations by laser Doppler scanning in the cortex during the experiment in bilateral hemispheres(at control phase, after the left carotid artery ligation, during ischemia and after hypotension). The physiological variable such as blood pressure and gas analysis were within normal range in all groups. There were no differences of rCBF between the right and left hemispheres in group A during the experiment. In group A, rCBF of both hemispheres significantly decreased after the ligation of the left carotid artery, during the induced ischemia (P < 0.05), and recovered to the value of before ischemia. Whereas, in group B rCBF of the left side(non-occluded side) decreased after the ligation of the left carotid artery, during the induced ischemia(P < 0.05), and recovered to the value of before ischemia, but rCBF of the right side(occluded side) decreased only during the induced ischemia(P < 0.05) and rCBF of the right side was significantly higher than the left brain after ligation of the carotid artery, during ischemia and after hypotension(P < 0.05). On the basis of these data, we concluded that cerebrovascular adaptations can be acquired by 3 days after unilateral carotid artery occlusion and the tolerance phenomenon is certainly attributed to microcirculatory improvement.     

Inorganic antimicrobial coating for titanium alloy and its effect on bacteria

Background  For orthopedic implants, infection is a serious problem. Therefore, we considered an implant with antimicrobial ability can prevent infection. We tried to coat a titanium alloy surface with Novaron, a commercially available inorganic antimicrobial. The purpose of this study was to analyze the differences among the surfaces of materials coated using different processing pressures of the working gas and analysis of the antimicrobial activity. Methods  One of the inorganic antimicrobials Novaron (grade VZ 600) was applied to titanium alloy (Ti6Al4V) plates. This antimicrobial has limited heat resistance, so we used cold spray technology to coat the titanium alloy with it. The principle of cold spray technology is spraying a powder in a high-velocity gas jet, accelerated by adiabatic expansion, against a substrate. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) were used to analyze the differences among the surfaces of materials coated using different processing pressures of the working gas. The Japanese Industrial Standard (JIS) method (JIS Z2801: 2000) was used to analyze the antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Antimicrobial activity was analyzed only for the sample coated at 3.0 MPa. Results  The SEM and EDS results indicated that when the pressure of the working gas was increased, the antimicrobial coated the titanium adequately. This material showed good effects against S. aureus and P. aeruginosa and some effect for K. pneumoniae. Conclusions  Antimicrobial implants represent a preventive method against infection. There is a possibility of using them not only for clean operations but also for operations with suspected bacterial contamination, such as fixation of slight compound fractures.     

Microsurgical treatment of patients with vestibular and cochlear symptoms

Eighteen patients with vertigo, tinnitus, and various hearing disturbances were treated by posterior fossa exploration and microvascular decompression of the eighth cranial nerve; they were followed for more than 3 years. After successful decompression of the eighth nerve from offending vessels, the attacks of vertigo disappeared in 11 patients, improved markedly in 3 patients, and improved mildly in 4 patients. The tinnitus vanished in three patients and decreased in nine. The hearing disturbance improved in only five patients and worsened in three. Because of the satisfactory improvement of the attacks of vertigo, which are the most distressing symptoms for patients, we recommend surgical exploration for patients with severe symptoms of vestibular disturbances.     

Correlation between spinal cord blood flow and arterial diameter following acute spinal cord injury in rats

Summary Simultaneous measurements of spinal cord blood flow and arterial diameter at areas adjacent to a site of spinal cord injury were carried out to determine changes in CO₂ reactivity and autoregulation. The spinal cord injury was made at T10 level by the epidural clip compression method. A spinal window was drilled at an area either 7 mm caudal or 7 mm rostral to the injury site for the measurement of spinal cord blood flow and arterial diameter at the same time. Spinal cord blood flow was decreased at both spinal windows, especially at the rostral window. Arterial diameter was also decreased significantly at both sites. The ischaemic zone evaluated histologically tended to expand more diffusely in the rostral direction than in the caudal direction.In the pre-injury stage, both CO₂ reactivity and autoregulation were present in the spinal cord. Following the clip injury, CO₂ reactivity and autoregulation were both impaired in the areas 7 mm adjacent to the impact site. Correlation coefficients suggested that the rostral spinal cord tended to sustain more injury than the caudal spinal cord.The histologically proven spinal cord ischaemia following the injury may have resulted from the decreased arterial diameter and impaired CO₂ reactivity and dysautoregulation of the spinal cord.     

Bioluminescence of the Ca2+-binding photoprotein aequorin after cysteine modification.

Aequorin is a monomeric Ca2+-binding protein (Mr, 21,400) that emits light upon reacting with Ca2+. The protein has three Ca2+-binding sites, three cysteine residues, and a noncovalently bound chromophore that consists of coelenterazine and molecular oxygen. Light is emitted via an intramolecular reaction in which coelenterazine is oxidized by the bound oxygen. After light emission, aequorin may be regenerated by incubating the protein with coelenterazine, dissolved oxygen, EDTA, and 2-mercaptoethanol. To understand structure-function relationships in this protein, we used the technique of site-specific mutagenesis to replace the three cysteine residues with serine. Six of the seven modified aequorins had reduced luminescence activity, whereas the seventh with all three cysteines replaced by serine had luminescence activity equal to or greater than that of the wild-type aequorin. Further, the time required for the regeneration of the triply substituted aequorin was substantially increased compared to the time required for the regeneration of the wild-type aequorin. The results suggest that cysteine plays an important role in the regeneration of aequorin but not in its catalytic activity.