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Biomedical subjects

Z Ye

Publications and source records attributed to Z Ye.

At least 127 records · Page 7Linked to original sources
PubMed1994

Reversal of chloroquine resistance in falciparum malaria by some calcium channel inhibitors and optical isomers is independent of calcium channel blockade.

Various types of calcium channel blockers verapamil, gallopamil, devapamil, diltiazem, and nifedipine and a calmodulin inhibitor R24571 were evaluated for reversal of chloroquine(CQ) resistance of Plasmodium falciparum in an in vitro system. The results demonstrated that some of the above Ca2+ antagonists such as verapamil, gallopamil, devapamil and diltiazem were found to exert remarkable reversal activity of CQ resistance of the falciparum parasite in vitro, while the others like nifedipine and R24571 had no reversal properties of CQ resistance of the parasite. In addition, reversal activities of the CQ resistance by enantiomers of some calcium channel blockers(R-(+)-verapamil, R-(+)-gallopamil and R-(+)-devapamil), which do not bind to the calcium channel, were also observed in this study. The data strongly indicate that the mechanism of reversal of CQ resistance of falciparum malaria in vitro is independent of the calcium channel.

Animals↗
PubMed1993

Total serum cholesterol levels and mortality risk as a function of age. A report based on the Framingham data.

OBJECTIVE: To evaluate the relationship between serum cholesterol level and all-cause, coronary heart disease (CHD), and non-CHD mortality as a function of age. METHODS: The data source was the biennial examination data from 1948 through 1980 for the 5209 men and women enrolled in the Framingham Heart Study. Age-specific analyses by the Cox proportional hazards regression model were performed of survival subsequent to ages 40, 50, 60, 70, and 80 years for all subjects enrolled and alive at each of the stated ages. Complementary models were studied that used high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or total cholesterol level as predictors of survival subsequent to the examination at which lipoprotein subfractions were determined (1968) through 1973). RESULTS: The relationship between total cholesterol level and all-cause mortality was positive (ie, higher cholesterol level associated with higher mortality) at age 40 years, negative at age 80 years, and negligible at ages 50 to 70 years. The relationship with CHD mortality was significantly positive at ages 40, 50, and 60 years but attenuated with age until the relationship was positive, but not significant, at age 70 years and negative, but not significant, at age 80 years. Results for the relationship between low-density lipoprotein cholesterol and high-density lipoprotein cholesterol and mortality help explain these findings. Non-CHD mortality was significantly negatively related to cholesterol level for ages 50 years and above. The negative results in the oldest age group for all-cause and CHD morality appeared to be due to a negative relationship with low-density lipoprotein cholesterol levels rather than the protective effect of high high-density lipoprotein cholesterol levels. Similar results from several modified analyses make low cholesterol level due to severe illness an unlikely explanation for our results. CONCLUSIONS: Physicians should be cautious about initiating cholesterol-lowering treatment in men and women above 65 to 70 years of age. Only randomized clinical trials in older people can settle the debate over the efficacy and cost-effectiveness of lipid-lowering interventions for reducing mortality and morbidity in this population.

Adult↗
PubMed1993

Aggressive oligodendroglioma predicted by chromosome 10 restriction fragment length polymorphism analysis. Case study.

Oligodendrogliomas are indolent brain tumors with mean postoperative survival of about 5 years. However, the range of postoperative survivals is wide, suggesting that these tumors are heterogeneous in their biologic behavior. Using restriction fragment length polymorphism (RFLP) analysis, we studied a case of an oligodendroglioma with loss of chromosome 10 sequences, a finding that has only been reported in glioblastoma multiforme and anaplastic astrocytomas. Four and a half months after the initial surgery the patient returned with a recurrent tumor having classic radiologic and pathologic features of glioblastoma multiforme. Loss of chromosome 10 alleles in oligodendroglioma may be predictive of aggressive biologic behavior, even in the absence of recognized histopathologic characteristics of anaplasia, and may enable us to select more appropriate treatments for this group of patients.

Alleles↗
PubMed1993

The extrinsic blood supply of the ulnar nerve at the elbow: an anatomic study.

The extrinsic vasculature of the ulnar nerve as it relates to the treatment of cubital tunnel syndrome has not previously been described in detail. For a study of the anatomy, 18 fresh-frozen cadaver upper limbs were dissected after intra-arterial injection of latex. Two major pedicles were present in all 18 specimens--the superior ulnar collateral artery proximally and the posterior ulnar recurrent artery distally. A single minor pedicle, the inferior ulnar collateral artery, was present in 5 of 18 specimens. Total vessel length as well as distance to the medial epicondyle for the extrinsic arteries was measured. On the basis of these anatomic dissections, it is suggested that the extrinsic vascular supply can be preserved during anterior transposition of the ulnar nerve, even after extensive mobilization of the nerve.

Arteries↗
PubMed1993

Loss of heterozygosity for alleles on chromosome 10 in human brain tumours.

We analysed for loss of alleles on chromosome 10, 25 astrocytomas, 3 ependymomas, 2 medulloblastomas, 2 juvenile pilocytic astrocytomas, 2 gangliogliomas, 1 subependymal giant cell astrocytoma and 1 anaplastic oligoastrocytoma. A battery of 12 DNA markers spanning chromosome 10 was employed. Loss of heterozygosity on chromosome 10 was seen in 16 tumours (13 glioblastoma multiforme, 2 anaplastic astrocytomas, and 1 anaplastic oligoastrocytoma), but not in any of the low-grade astrocytomas examined. High-resolution restriction fragment length polymorphism (RFLP) analysis showed that the loss of alleles in a number of tumours involved two separate large regions of chromosome 10 (10p-proximal 10q and distal 10q). However, a small common region of deletion overlap could not be identified. Our data indicate that the loss of alleles on chromosome 10 is a common finding, seen in over two-thirds of malignant astrocytomas, and may be suggestive of the presence of two or more chromosome 10 tumour suppressor genes involved in astrocytoma formation. Nevertheless, the possibility of these genetic changes being secondary and not causative of the deregulated cell growth cannot be excluded. Regardless of the mechanisms involved, however, chromosome 10 deletions may be a genetic marker for malignant astrocytomas.

Alleles↗
PubMed1993

Frequency of p53 tumor suppressor gene mutations in human primary brain tumors.

Mutations in the p53 tumor suppressor gene are the most common genetic alterations found in diverse types of human cancer, including the primary malignant brain tumor, glioblastoma multiforme. To estimate the frequency of p53 mutations in human brain tumors, we screened 120 human primary brain tumors (59 astrocytic; 61 nonastrocytic) by the polymerase chain reaction-single-strand conformation polymorphism technique. Six astrocytic tumors (one anaplastic astrocytoma and five glioblastoma multiforme) were found to have putative p53 mutations. Direct sequencing of polymerase chain reaction-amplified deoxyribonucleic acid from these six tumors confirmed the presence of different point mutations in the conserved regions of the p53 gene. Allelic losses on chromosome 17p were detected in four (67%) of the six tumors with p53 mutations. p53 mutations were not detected in any of the 61 nonastrocytic brain tumors. Also, polymerase chain reaction-single-strand conformation polymorphism analysis of 74 leukocyte deoxyribonucleic acid samples from patients with astrocytic and nonastrocytic brain tumors failed to detect any germ-line p53 mutations. We conclude from these findings that p53 gene mutations in brain neoplasms are primarily limited to tumors of astrocytic origin and that the p53 gene mutations in sporadic astrocytomas are somatic in origin (i.e., nonprenatally determined).

Alleles↗
PubMed1993

Alpha-adrenergic receptor responsiveness in vascular smooth muscle of canine bone.

In an ex vivo canine tibial preparation, an alpha-1-adrenergic antagonist (prazosin, 212 ng.ml-1.minute-1) markedly attenuated the effect of high intraluminal doses (greater than 0.5 mg) of norepinephrine but was less effective at lower doses. An alpha-2-adrenergic antagonist (rauwolscine, 198 ng/ml/minute) was more effective than prazosin in blocking the vascular smooth muscle contraction evoked by low doses of norepinephrine (greater than 0.125 mg). Cirazoline, an alpha-1-adrenergic agonist, had a potent contractile effect on smooth muscle at high concentrations (5 x 10(-6) M), whereas the alpha-2-adrenergic agonist UK14304 was more effective at low concentrations (1 x 10(-7) M). Thus, in the vascular smooth muscle of canine tibia there is a mixed population of postjunctional alpha-1 and alpha-2-adrenergic receptors that exhibits a dose-dependent responsiveness. Adrenergic receptor mechanisms may contribute to alterations in bone blood flow. This may be relevant to impaired reperfusion after microvascular bone transfer. Furthermore, adrenergic receptor mechanisms may help explain variations in bone blood flow related to systemic, regional humoral, or metabolic factors.

Adrenergic alpha-Agonists↗
PubMed1993

Small area variation analysis. Methods for comparing several diagnosis-related groups.

In small-area variation analysis, the variation of health care utilization rates, e.g., admission rates, among small areas is calculated. Frequently, the variation of one diagnosis, diagnosis-related group (DRG), or procedure is compared with the variation of another. Unfortunately, the methods generally used to make these comparisons are not consistent. They differ on whether they 1) adjust for the prevalence of the DRGs, 2) distinguish between variation among areas and variation within areas, 3) weight all areas equally, and 4) adjust for multiple admissions per person. None has an associated confidence interval. These discrepancies occur in part because there is no statistical model of small area variation. Without such a model, it is not known how to measure variation, and thus, it is not known how to compare different DRGs. Here, the authors use data on 473 DRGs from 28 counties in Washington state to study the nature of variability. The variation was higher for the more prevalent DRGs, suggesting that adjusting for prevalence may be reasonable. The true coefficient of variation appears to be a "natural" measure of variation, but the usual small area variation statistics do not provide good estimates of the true coefficient of variation. A new estimate is proposed that can be used to compare and test the variability of several DRGs.

Analysis of Variance↗
PubMed1992

Free flap transfer of the cutaneous maximus muscle in the rat: comparison to the latissimus dorsi muscle flap.

A new rat model of free muscle flap transfer is presented. Microvascular transplantation of the cutaneous maximus muscle flap is performed at the groin site, with anastomosis of the axillary vessels to the appropriate femoral vessels. This muscle flap has many useful attributes for experimental manipulation. It has a high success rate following transplantation, the anatomy is consistent, the dissection is straightforward, the length of pedicle is relatively long (10 mm), the vessels for repair are of sufficient size (1.0-1.35 mm diameter), and the microsurgical procedure can be performed in a relatively short period. The donor site deficit causes minimal impairment to animal mobility, and no evidence of limb ischemia is noted after ligation of the axillary vessels. The cutaneous area adjacent to the muscle is perfused by muscular perforators supplied by the flap pedicle; thus a skin island may be used to monitor the flap or to create a composite myocutaneous transfer. The cutaneous maximus muscle has mixed muscle types and anatomic dimensions similar to those of the latissimus dorsi muscle, and it provides ample tissue for pharmacological and biochemical studies, yet it presents easier dissection and microanastomoses than the latissimus flap, with more potential for versatility in application. The advantages of this muscle flap make it a very useful experimental model for flap transfer research.

Animals↗
PubMed1992

Functionalized, probe-containing, latex nanospheres.

Synthesis of surface-functionalized, probe-containing latex nanospheres is described. Approximately 40,000 probe ions may be encapsulated in a nanosphere of 50 nm diameter. The probe may be a radionuclide or a lanthanide with long-lived fluorescence. Alternatively, a "cargo" of pharmaceutical interest may be used. The surface of each nanosphere contains thousands of acid groups which may be functionalized for subsequent attachment to biomolecules such as antibodies. Functionalized nanospheres have been successfully coupled to a tobacco virus.

Biotin↗
PubMed1992

A search for X-chromosome uniparental disomy and DNA rearrangements in the Rett syndrome.

The cause of the Rett syndrome remains unknown but is thought to be related to X-chromosome abnormalities. Restriction fragment length polymorphism analysis was employed to search for X-chromosome DNA rearrangements and uniparental disomy in 16 probands and their families. Eighteen different probes, each specific for an area on either the long or the short arm of the X-chromosome, were used. DNA rearrangements were not detected at any of the tested loci. In addition, at each informative locus evidence of both maternal and paternal contributions was found in all probands. Thus, no evidence of either chromosomal abnormality or uniparental disomy was found in the population studied. If uniparental disomy is indeed a causative genetic mechanism for the Rett syndrome, its occurrence may only be infrequent.

Adolescent↗
PubMed1992

The occipital artery flap for transfer of hair-bearing tissue.

The posterior scalp is investigated as the donor site for the transfer of hair-bearing tissue based on the occipital artery. The dissection of fresh cadavers was performed and the occipital artery was noted to have three major branches including a vertical, transverse, and descending branch. The vessel connection across the midline allowed transfer of the posterior scalp to the desired recipient site. This vessel provides the possibility of transfer of large areas of hair-bearing tissue to a single stage. The variability of flap design is described as well as the technical considerations for a successful transfer.

Adult↗
PubMed1992

Coverage of widely separate defects of the lower extremity: application of cluster analysis.

A patient with lower extremity reconstruction is presented with a radial forearm free flap designed using the cluster analysis method of cutaneous perforators. The cutaneous vascular anatomy of fasciocutaneous flaps is discussed as well as the application of the mathematical model of analysis of the vascular territories within specific flaps to assist in "custom" flap design. The ultimate goal of this technique is the creation of flaps that provide a more precise and anatomical reconstruction of the proposed defect.

Adult↗