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Q Cai

Publications and source records attributed to Q Cai.

97 records · Page 6Linked to original sources
PubMed1990

Natural killer cell responses in homosexual men with early HIV infection.

Natural killer (NK) cells may be of significance in host defense against viral infections. In the present study, NK cell function was examined in relation to different phases of human immunodeficiency virus (HIV) infection. Peripheral blood mononuclear cells were tested for NK cell activity using K562 cell targets in a 51Cr-release assay. NK cell responses of 26 HIV-seronegative homosexual men were not significantly different from those of 30 heterosexual controls. NK activity was significantly lower in cells from 32 homosexual men with documented, early-phase HIV infection (average of 14 months; range of 3-27 months) as compared with that of seronegative men. The NK cell response decreased with time, since men within the first year of infection (n = 15; average of 7.8 months; range of 3-12 months) had greater NK cell activity than did those with longer duration of infection (n = 17; average of 18.3 months; range of 13-27 months). The decrease in NK cell activity did not correlate with altered numbers of cells bearing CD16 (NK) markers in these subjects. NK cell-mediated lysis and cell numbers were most severely depressed in a separate group of HIV-seropositive men who had acquired immune deficiency syndrome (AIDS). In vitro treatment with alpha-interferon (alpha-IFN) significantly enhanced NK activity of effector cells obtained from men within the first year of HIV infection but not in those with longer-term infection. Our results indicate that NK cell function decreases over time within the first 2 years of HIV infection in homosexual men, and is lowest in HIV-seropositive men with overt AIDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1990

Recent studies on the biological actions of vitamin D on intestinal transport and the electrophysiology of peripheral nerve and cardiac muscle.

Vitamin D, with parathyroid hormone and calcitonin, is an essential factor in the homeostatic regulation of systemic calcium in most vertebrate species. Targets for this aspect of vitamin D action, through its biologically active metabolites, are primarily the intestine, kidney and bone. Each of these tissues or organs are stimulated by 1,25(OH)2D3 to increase the transport calcium into the extracellular fluid compartment when plasma calcium levels are below normal and/or when there is a greater need for calcium to meet the requirements of physiological processes, such as growth, gestation and lactation. During such periods, the efficiency of the absorption of calcium from the intestine increases, the resorption of calcium salts from bone is stimulated, and the efficiency of the reabsorption of filtered calcium by the renal tubule is increased. In addition to the homeostatic function of vitamin D, there is an increasing amount of evidence that vitamin D has important effects on tissues and organs other than those concerned with calcium homeostasis. With regard to the intestinal epithelial system, the genomic effect of 1,25(OH)2D3 was shown several years ago when the de novo synthesis of a specific vitamin D-induced calcium-binding protein (CaBP, calbindin-D) was demonstrated. In our view, this appears to be an essential factor in the well-documented enhancement of calcium absorption by vitamin D. The function of calbindin-D, a high affinity calcium-binding protein, in the absorptive process is not precisely known but currently considered to act as an intracellular facilitator of the diffusion of calcium from the microvillar pole of the enterocyte to the basal-lateral membrane. There is evidence that vitamin D influences another step in the absorptive process. This step appears to be associated with the entrance of luminal calcium into the enterocyte, the first step in the transepithelial transport process. This response appears to occur relatively early (1 h or less) after 1,25(OH)2D3 is given to vitamin D-deficient animals, whereas the de novo synthesis of transport proteins has a much longer lag time (about 4 h). The in vitro absorption studies of Nemere et al (1984) and the in vivo experiments of our group (Wasserman et al, 1982) accentuate this point. However, the more rapid reaction, i.e., the possible modification of the permeability properties of the brush border membrane, does not result in a substantive increase in overall calcium absorption unless the enterocyte had been "primed" by previous exposure to vitamin D. The "priming" reaction might represent the synthesis of CaBP or some other intracellular component.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Prevalence of the plasma bovine leukaemia virus blocking factor in cattle from a commercial dairy herd.

The prevalence of the plasma bovine leukaemia virus blocking factor was examined in a commercial herd. The detection of the blocking factor activity depended on the nature of the infected target cells used in the assay. Using the sensitive bovine leukaemia virus-infected target lymphocytes, the factor was found to be significantly more prevalent in infected cattle than in virus-free cattle. Furthermore, in infected cattle, no correlation was observed between the level of bovine leukaemia virus antibody and the presence of the blocking factor.

Animals↗
PubMedDate not supplied

Age-dependent increase of indigenous DNA adducts in rat brain is associated with a lipid peroxidation product.

Indigenous DNA adducts (I-compounds) are considered to be a biomarker of aging tissues. Thus far, few studies have been conducted to investigate the accumulation patterns of I-compounds in the brain during aging. Particularly, identities of age-dependent I-compounds have largely remained unknown. In the current study, we have determined the amounts of I-compounds in the brains of male Fischer 344 rats at ages 1, 6, 12, 18, and 24 months using a 32P-postlabeling technique. The results indicate that I-compounds increase in the rat brain age dependently from 6 to 24 months of age. Total I-adduct levels (central and upper cutouts) increase 3.5-fold from 6 to 24 months. Contrary to the results of other investigators, brains of 1-month-old rats contain the highest level of I-compounds, which may be due to the hypermetabolic status during the infant period. In an effort to characterize I-compounds, different deoxynucleosides were coincubated with malondialdehyde (MDA). The results show that only deoxyguanosine (dGMP)-MDA adducts overlap with I-compounds of the rat brain DNA adducts map. A total of five dGMP-MDA adducts have been identified as responsible for I-compounds in brain tissues. It is known that brain tissue contains high levels of lipids that are susceptible to oxygen free radicals and that MDA is the most abundant and genotoxic product of lipid peroxidation. The present study provides supporting evidence that lipid peroxidation and its product (MDA) may play an important role in endogenous brain DNA modification, which may partly contribute to cerebral aging and age-related degenerative disorders of the brain. The accumulation of I-compounds with aging may serve as an index of indirect oxidative damage to DNA as evidenced by the presence of MDA-DNA adducts.

Aging↗
PubMedDate not supplied

Anterior intervertebral disc excision and bone grafting in cervical spondylotic myelopathy.

An analysis of 121 cases of cervical spondylotic myelopathy treated by anterior excision of the disc and fusion was undertaken. All patients were followed at least six months, and follow-up averaged 22 months. Results showed that 97.5% of patients had no aggravation of symptoms, 90.9% were improved, and 72.6% were able to resume normal activity. Surgical intervention can greatly improve the prospects of patients with severe cervical spondylotic myelopathy, and its use should not be lightly ruled out. Autografts yield higher fusion rates and better overall results than homografts. Selection of the number and level of discs to be excised depends upon clinical and roentgenographic indications, as well as the myelogram and the amount of fluid injected into the discs.

Adult↗