Biomedical subjects

Y Cao

Publications and source records attributed to Y Cao.

546 records · Page 31Linked to original sources

PubMedDate not supplied

Bispecific antibodies as novel bioconjugates.

Bispecific antibodies are unique macromolecular heterobifunctional cross-linkers with two different binding specificities within a single molecule. As ideal bioconjugates, they can specifically glue any two different molecules together without the need for chemical conjugation. With this unique feature, they have immense potential in biological and immunological fields. Their applications range from immunohistochemistry, immunoassays, radioimmunodiagnosis, radioimmunotherapy, and immunotherapy. Recently, a new second generation of bispecific molecules, bispecific single chain Fv and diabodies, has been produced by DNA recombinant technology. They can be considered as the ultimate magic bullets for in vivo applications. They may theoretically improve tumor or pathogen targeting and minimize side effects, eventually replacing the full-length bispecific antibodies. Emphasizing on developmental methodology and clinical applications of bispecific antibodies, this review gives a bird's-eye view of these unique bioconjugates.

Animals↗

PubMedDate not supplied

The occipital cortex is hyperexcitable in migraine: experimental evidence.

OBJECTIVES: Threshold for generation of magnetophosphenes has been reported to be lower in migraine. We compared the threshold for eliciting phosphenes by transcranial magnetic stimulation and the ability to visually trigger headache in a select group of individuals with migraine with and without aura to normal controls. METHODS: Transcranial magnetic stimulation was performed using the Cadwell MES-10 stimulator. A circular coil, 9.5 cm in diameter, was applied to the occipital scalp (7 cm above the inion). Stimulator intensity was increased in 10% increments until subjects reported visual phenomena or 100% intensity was reached. Stimulator intensity was then fine-tuned to determine the threshold at which phosphenes were seen. In the same subjects, visual stimulation was given in 3.0 T MRI and if a headache occurred the response was recorded. RESULTS: Fifteen subjects with migraine were compared to 8 controls. A significant proportion of the migraineurs (86.7%) developed phosphenes compared to the controls (25%) (P = .006). The probability of triggering a headache was also higher in the migraineurs (53%); no headache was triggered in the controls (P = .019). A significant correlation was found between the threshold for phosphenes on transcranial magnetic stimulation and visually triggered headache (P = .002). When only migraine was considered, there was again a significant trend (P = .084). CONCLUSIONS: There is a difference in threshold for excitability of occipital cortex in migraineurs and controls. The hyperexcitable visual cortex in migraine is predisposed to visually triggered headache.

Adult↗

PubMedDate not supplied

Magnetic resonance assessment of acute and chronic stroke.

This article describes the important role of magnetic resonance imaging (MRI) in noninvasively assessing human focal ischemic stroke. Conventional MRI, diffusion-weighted and/or perfusion-weighted imaging have been used to facilitate both the qualitative and quantitative evaluation of heterogeneity of ischemic brain tissue. Further, by combining 2 or more magnetic resonance parameters, tissue-signature models have been developed that may be used as surrogate markers of tissue histopathology to characterize ischemic tissue as salvageable, necrotic, or tissue in transition to necrosis. Magnetic resonance tissue-signature models and results are presented. Dynamic changes in the evolution of ischemic tissue to infarction are also discussed. Recovery from acute stroke was studied with blood oxygenation level-dependent functional MRI to investigate the neural mechanisms for recovery from aphasia after stroke.

Acute Disease↗

PubMedDate not supplied

Glutamine enhances gut glutathione production.

BACKGROUND: The gastrointestinal tract is recognized as having important metabolic functions. This study examined gut glutathione (GSH) extraction and the effect of supplemental oral glutamine (GLN) on gut GSH fractional release. METHODS: Healthy female Fisher-344 rats weighing approximately 150 to 200 g were pair-fed chow and supplemented by gavage with 1 g/kg/d GLN or an isonitrogenous amount of Freamine (McGaw, St. Louis, MO). Rats were sacrificed at 6 weeks. Arterial and portal blood was assayed for GLN and GSH content. The gut GLN and GSH extractions were calculated. RESULTS: The gut GLN fractional uptake was increased by approximately 50%, and there was a near threefold increase in gut GSH fractional release in the GLN-supplemented group. CONCLUSIONS: The discovery of gut's role as a major producer of GSH may give insight into why feeding via the gut rather than by the venous route is so important. Supplemental oral GLN further enhances GLN extraction as well as GSH fractional release in the gut.

Animals↗

PubMedDate not supplied

A simple and efficient method for radiolabeling of preformed liposomes.

A simple and efficient method for radiolabeling preformed liposomes was developed using hepatobiliary imaging agent (99m)Tc-diisopropyl iminodiacetic acid ((99m)Tc-DISIDA). Chloroform extraction of (99m)Tc-DISIDA from aqueous solutions results in 80% radioactivity in the organic phase due to its lipophilic properties. However, with the presence of reduced glutathione (gamma-Glu-Cys-Gly), chloroform extraction results in only 30% of label in the organic phase because the (99m)Tc-DISIDA complex undergoes reduction decomposition to more hydrophilic species by reaction with glutathione. The incorporation efficiency of the (99m)Tc-DISIDA into the liposomes containing reduced glutathione was greater than 90%. The labeled liposomes were stable up to 24 h in saline and 90% FBS after preparation. Biodistribution studies in mice showed that (99m)Tc labeled liposomes accumulated in liver and spleen at 24 h postinjection, unlike (99m)Tc-DISIDA. Compared to hexamethylpropyleneamine oxime (HMPAO), the (99m)Tc-DISIDA compound is much cheaper and has a longer shelf life when used for liposome labeling. The labeling technique described here could be used for monitoring pharmacokinetic and pharmacodynamic changes of liposomes, and tumor or infection imaging when coupled with targeting antibodies.

Animals↗

PubMedDate not supplied

No point mutation but a codon 31ser-->arg polymorphism of the WAF-1/CIP-1/p21 tumor suppressor gene in nasopharyngeal carcinoma (NPC): the polymorphism distinguishes Caucasians from Chinese.

Mutational inactivation of the p53 tumor suppressor gene is an infrequent event in human nasopharyngeal carcinoma (NPC), a malignancy showing a high incidence in southern China and southeast Asia. To examine the possible involvement of an activated p53 pathway in nasopharynx carcinogenesis, we have screened primary NPC biopsies for possible point mutations in WAF-1/CIP-1/p21, an effector gene transcriptionally regulated by and functioning as a mediator of the p53 tumor suppressor gene. Mutations in WAF-1/CIP-1/p21 might mimic p53 mutations in tumors having wild-type p53 such as most NPCs. The mutational analysis of WAF/CIP/p21 by PCR-single strand conformational polymorphism-direct sequencing revealed no point mutation in 41 primary NPC biopsies. A codon 31ser-->arg polymorphism was, however, detected. A striking difference in the distribution of the serine (WAF-ser) and arginine (WAF-arg) forms of WAF-1/CIP-1/p21 was observed when normal healthy Caucasians and Chinese were compared (P < 0.0001). The majority of Caucasians examined were found to be homozygous for WAF-ser (89%, n = 65), while Chinese living in areas of high NPC incidence show a greater than 86% homozygous or heterozygous WAF-arg (Taiwan, n = 66; Hunan, n = 32). The two forms of WAF-1/CIP-1/p21 were examined for potential functional differences in their ability to inhibit cyclin-dependent kinases and tumor cell growth. No significant differences were detected. Furthermore, no association between WAF-1/CIP-1/p21 genotype and NPC risk was observed in a case-control study of 76 NPC cases and 66 normal controls conducted in Taiwan.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗