[Effects of heat and noise environments on lipid peroxidation erythrocyte membrane in pilots].

OBJECTIVE: To investigate the effects of heat and noise environments on lipid peroxidation of erythrocyte membrane in pilots. METHOD: Twenty-four pilots and twenty-one ground personnel (control group) served as the subjects. The pilots performed flying in heat and noise environments. Glutathione peroxidase (GSHpx) and malondialdehyde [correction of malondiadehyde] (MDA) levels in erythrocyte membrane were determined before flying (6:00 a.m.), immediately after flying (12:00 a.m.) and 8 hours after flying (8:00 p.m.) respectively with a spectrophotometer. RESULT: Immediately after flying, GSHpx activity in pilot's erythrocyte membrane decreased significantly as compared with that in control group. Immediately after flying and 8 h after flying, MDA contents in pilots increased significantly as compared with that of control group. CONCLUSION: Heat and noise environments might induce increase of lipid peroxidation reaction and decrease of antioxidant ability.

[Effects of acute hypoxia on plasma lactic acid and lactic dehydrogenase content in pilots].

Objective. To study the effect of acute moderate hypoxia on plasma lactic acid (LA) and lactic dehydrogenase (LDH) content in pilots. Method. Concentrations of plasma LA and LDH were measured by colorimetry in 16 healthy male pilots in the early morning (6:00 a.m.), following acute moderate hypoxic exposure (10:00 a.m.) and 6 hours after returned to the ground (4:00 p.m.). 16 healthy male ground people served as control group, and their plasma LA and LDH contents were assayed at corresponding time. Result. Plasma LA after moderate hypoxic exposure in the pilot group was significantly higher than that at 6:00 a.m., 4:00 p.m., and control group (P < 0.01). While the content at 6:00 a.m., 4:00 p.m. in pilot group was not significantly different from the control group (P > 0.05). The content of plasma LDH after moderate hypoxic exposure in the pilot group was not significantly higher than that at 6:00 a.m., 4:00 p.m., and control group (P > 0.05). Conclusion. Acute moderate hypoxia can make the plasma LA content increase in pilots, and reach to the normal level within 6 h. While the LDH content has no significantly change.

Effects of high temperature and noise on erythrocyte membrane ATPase activity in pilots during flight.

Objective. To determine the effect of heat and noise on erythrocyte membrane ATPase activities in pilots during flying. Method. Twenty-four pilots performing bombing for 3 h (45-53 degrees C, 122-97 dB in the cabin) served as the subjects. 21 ground personnel served as control (27 degrees C in the room). Blood samples were taken from both groups before flying (6:00 a.m.), and immediately (12:00 a.m.) and 8 h (8:00 p.m.) after flying. Na(+)-K+ ATPase, and Ca2(+)-Mg2+ ATPase activities in erythrocyte membrane were determined with colorimetry. Result. The Na(+)-K+ ATPase activity in erythrocyte membrane at 6:00 a.m. in pilots was higher than that in control group at the same time (P<0.01). The Ca2(+)-Mg2+ ATPase activities in erythrocyte membrane at 12:00 a.m. and 8:00 p.m. in pilots were significantly higher, compared with those in control group at the same time (P<0.01). Conclusion. The ATPase values obtained in our study were all within normal range, and the daytime variation of both groups are the same. Exposure of human body to heat and noise for long time may be harmful, the higher ATPase activity is, the more catabolism of ATP will be. ATP exhaustion will lead to Ca2+ overload in erythrocyte thus stiffen the red cell membrane.

Isolation, mapping, DNA sequence and RFLPs studies of random single-copy DNA segments on human X chromosome.

Using the total human/mouse DNA as the probe, screening has been carried out three times with in situ plaque hybridization to obtain the single-copy DNA sequence from the human X chromosome genomic library. The effective rate of screening is 1.45%. DNAs from clones containing single-copy inserts have been analyzed by a panel of hybrid cells with or without human X chromosome. Three segments, designated by DXFD52,73,75, are mapped to the X chromosome. DXFD52 has been precisely localized on Xq12-q13 with in situ chromosomal hybridization. DXFD52 has been partially sequenced. The results indicate that DXFD52 is a new isolated single-copy segment on the X chromosome. Great progress in the RFLPs study with DXFD52 has been achieved in the population of Chongqing, Sichuan Province. The results show that the DXFD52 can be used to detect the RFLP with Hind III, Bgl II, and Hinf I. DXFD52 will be a potential "landmark" for the construction of the complete linkage map of human genome and the analysis of genomic sequence. And also, the results provide the experience in the development of a useful DNA probe to be applied to diagnosing X-linked disorders.

Comparison of four neural net learning methods for dynamic system identification.

Four types of neural net learning rules are discussed for dynamic system identification. It is shown that the feedforward network (FFN) pattern learning rule is a first-order approximation of the FFN-batch learning rule. As a result, pattern learning is valid for nonlinear activation networks provided the learning rate is small. For recurrent types of networks (RecNs), RecN-pattern learning is different from RecN-batch learning. However, the difference can be controlled by using small learning rates. While RecN-batch learning is strict in a mathematical sense, RecN-pattern learning is simple to implement and can be implemented in a real-time manner. Simulation results agree very well with the theorems derived. It is shown by simulation that for system identification problems, recurrent networks are less sensitive to noise.

[Preparation of human minisatellite DNA probes].

A 23-mer oligonucleotide based on the core sequence was chemically synthesized and used to screen the human genomic library. Fifteen positive recombinants containing the minisatellite sequences were identified, and one of them, C35.9, was used to perform Southern hybridization with the DNAs from unrelated Chinese individuals. Each sample has 3-11 hybridizing bands, and some of which are polymorphic. The band patterns detected under controlled condition are individual-specific in a limited population. This indicates that the minisatellites obtained by screening the library can be used to detect the polymorphisms of the minisatellites.

Four new DNA markers are assigned to the WAGR region of 11p13: isolation and regional assignment of 112 chromosome 11 anonymous DNA segments.

One hundred eighty-three human single copy clones were isolated from the Livermore Laboratory chromosome 11 library (ID code LL11NSO1) and 112 of them were mapped to chromosome 11. Using a panel of somatic cell hybrids segregating chromosome 11 translocations and short arm deletions, 54 of the clones were assigned to one of nine segments on the short arm of chromosome 11; the remainder were assigned to the long arm. Nine of these clones map to 11p13, and four of the nine [57(D11S89), 530(D11S90), 706(D11S93), and 1104(D11S95)] are confined to the same segment within p13 that contains catalase (CAT), the beta subunit of follicle stimulating hormone (FSHB), and the Wilms' tumor-aniridia (WAGR) gene complex.