A newly identified horseshoe crab lectin with specificity for blood group A antigen recognizes specific O-antigens of bacterial lipopolysaccharides.

A 14-kDa lectin, named tachylectin-3, was newly identified from hemocytes of the Japanese horseshoe crab, Tachypleus tridentatus. This lectin exhibited hemagglutinating activity against human A-type erythrocytes, but not against the B- and O-types of erythrocytes and animal erythrocytes, including those of sheep, rabbit, horse, and bovine. The hemagglutinating activity of tachylectin-3 was equivalent to that of a previously identified lectin, named tachylectin-2, with affinity for N-acetyl-D-glucosamine or N-acetyl-D-galactosamine. However, the activity of tachylectin-3 was not inhibited by these two N-acetylhexosamines at 100 mM but was inhibited by a blood group A-pentasaccharide at a minimum inhibitory concentration of 0.16 mM. Furthermore, the hemagglutinating activity was strongly inhibited by bacterial S-type lipopolysaccharides (LPSs) from Gram-negative bacteria but not by R-type LPSs lacking O-antigens. One of the most effective S-type LPSs was from Escherichia coli O111:B4, with a minimum inhibitory concentration of 6 ng/ml. These data suggest that tachylectin-3 specifically recognizes Gram-negative bacteria through the unique structural units of O-antigens. Ultracentrifugation analysis revealed that tachylectin-3 is present in dimer in solution. A cDNA coding for tachylectin-3 was isolated from a hemocyte cDNA library. Tachylectin-3 consisted of two repeating sequences, each with a partial sequence similarity to rinderpest virus neuraminidase. Tachylectin-3 and three previously isolated types of tachylectins were all predominantly expressed in hemocytes and released from hemocytes in response to external stimuli. These lectins present at injured sites suggest that they probably serve synergistically to accomplish an effective host defense against invading microbes.

Molecular and immunological characterization of a 64-kDa protein of Actinobacillus actinomycetemcomitans.

The 64-kDa protein to which about half the sera from patients with localized juvenile periodontitis and rapidly progressive periodontitis reacted strongly was purified from Actinobacillus actinomycetemcomitans Y4. Determination of the N-terminal sequence of the protein revealed that it was a GroEL-like protein. The DNA fragment containing the groEL gene of A. actinomycetemcomitans was amplified by polymerase chain reaction, and the groESL operon was cloned by using colony hybridization with the amplified fragment from A. actinomycetemcomitans chromosomal DNA. Sequence analysis revealed that structures of the operon and its products were typical in gram-negative bacteria. Rabbit polyclonal antibodies to the 64-kDa protein cross-reacted with approximately 65-kDa proteins of Haemophilus aphrophilus, Haemophilus influenzae, Haemophilus paraphrophilus, Escherichia coli and Eikenella corrodens but not with any cellular proteins of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum. It is possible that antibodies reactive to the 64-kDa protein in periodontitis patients are induced by the cross-reactivity with the hsp60 proteins of other bacteria.

An epidemiological study on cancer in certified arsenic poisoning patients in Toroku.

A mortality study has been made to assess the carcinogenic effect of arsenic exposure by analyzing a group of certified chronic arsenic poisoning patients at a small mining village in Japan. When compared with expected number of deaths, based on sex-, age-specific mortality of Japanese in 1975, '80 and '85, all cancer, cancer of respiratory system and cancer of bladder, kidney and other and unspecified urinary organs showed a significant excess over the expected number. Divided by employment history, death due to all cancers, to respiratory cancer and to urinary tract cancer showed a significant excess among former workers of the mine. Classified into four cohorts by both employment history and smoking habit, death from respiratory cancer showed a significant excess only in the cohort respiratory cancer showed a significant excess only in the cohort of former workers with smoking history, suggesting an interaction between exposure to arsenic and smoking. Eight cases among ten respiratory cancers and two urinary tract cancer cases were accompanied by cancer of other organs, including Bowen's disease.

Low-back pain among electric power supply workers and their attitude toward its prevention and the treatment.

Low-back pain among electric power supply workers and their opinions about the ways to prevent and relieve the disorder were investigated. A questionnaire study revealed that 38.7% of 6,272 electric power supply workers were suffering from low-back pain, including severe pain resulting in frequent absenteeism or requiring occasional rest from work. Chronological analysis of the occurrence of the disorder revealed that the incidence of gradually developing pain has increased and that improper working posture and overwork have become more important as etiological factors. Rest from work was found to be the most effective way of relieving pain, while any medical treatment which did not include rest was useless. Low-back pain among these workers is believed to have resulted from rapid and intensified work as required by increasing demand and mechanization, greater mental stress and improper working posture. As preventive measures, it is necessary to improve working hours and to lighten the rate of work. In order to relieve pain, the employers should permit the workers to absent themselves from work quickly following an attack. Discrepancy between workers' opinions and both actual causation of low-back pain and actual effectiveness of medical treatment is discussed.

Studies on the low back pain among electric construction workers. Report 2. Workers' attitude to the prevention and the treatment of their low back pain.

In the previous report, the author demonstrated that the electric construction workers were exposed to the high risk of low back pain, and discussed on the ways to prevent and to treat their occupational disorders. He concluded that the improvement of their working conditions, especially lessening of the working load, was necessary to prevent occupational low back pain, and that it was the most helpful effect on their low back pain to take a rest on an after the attack of the disorder, while most of the medical treatment without a rest were almost helpless. In this report, the author studied and discussed on the workers' opinions on the ways to prevent and to treat their low back pain, by means of questionnaire-method. The workers examined were classified by whether they had the disorder or not and also by the grades of their working load. The results are as follow: 1. As for preventive measures, it is the most popular opinion that they should take care not to hurt their low back; nevertheless, as a matter of fact, their low back pain has been mainly resulted from overwork. 2. As for necessary means on the attack of low back pain, many workers believe that medical treatment is the most helpful to the disorder. Fewer workers recognize the low back pain as an occupational disorder and have opinion that they should take a rest on the attack of the disorder. 3. There is much discrepancy between the workers' opinions mentioned above and the occupational health doctors' recommendations that it is most desirable to improve the working conditions and to let the workers take a rest. 4. The more seriously they suffer from the disorder, the more practical and reasonable are the contents of their opinions. 5. In order to let these workers take a rest from labour more easily, the employers should recognize their low back pain as an occupational disorder, including offjob-payment.