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Biomedical subjects

J Zhan

Publications and source records attributed to J Zhan.

29 records · Page 2Linked to original sources
PubMed1995

Radiologic manifestations of osteopetrosis.

The clinical radiologic manifestations of 8 patients with osteopetrosis (4 males and 4 females) are analyzed. Six of the cases are benign. The pathologic basis for the radiologic manifestations is discussed, and a classification is suggested. "Broom-like" metaphyses, metaphyses containing three or four dense layers of bone, and ossification of soft tissues around joints were found and differential diagnosis was made.

Adolescent↗
PubMed1994

Adhesion of sickle cells to vascular endothelium is critically dependent on changes in density and shape of the cells.

Experiments were performed to explore whether adhesion differences among different density sickle (SS) cells are mainly caused by deformability characteristics attendant to density variations, which could affect their surface contacts with the endothelium, or caused by any changes in their membrane surface (eg, receptors). Also, what is the contribution of morphologic attributes of SS cells in adhesive and obstructive events? To resolve these issues, controlled modifications of cell density were performed using Nystatin and sucrose. This allowed elevation of the mean corpuscular hemoglobin concentration (MCHC) of light-density SS2 discocytes to that of SS4 native dense cells, as well as its normalization in both native and artificially dehydrated cells. Hemodynamic and adhesive characteristics of these individual SS cell populations and their defined mixtures were investigated in the ex vivo mesocecum vasculature. Dehydrated (high MCHC) SS2 discocytes, alone or with SS2 control cells, caused a higher peripheral resistance but no persistent microvascular blockage. Nevertheless, dehydrated SS2 discocytes resulted in a significantly decreased adhesion in venules (adhesion sites). Rehydration of these high MCHC discocytes completely restored their adhesivity, similar to that of SS2 control cells. In contrast, irreversibly sickled cell (ISC)-rich SS4 dense cell class (dense discocytes and 66% to 72% ISCs) was less adherent than dehydrated SS2 discocytes, but caused a persistent blockage of small diameter postcapillary venules when infused with SS2 control or dehydrated discocytes. In the areas of adhesion, SS4 dense discocytes outnumbered ISCs by 4 to 1, demonstrating that ISCs, because of their shape characteristics, are minimally adherent but play a distinct role in postcapillary obstruction. When MCHC (density) of SS4 cells was decreased by rehydration, it resulted in an almost complete reversal of their hemodynamic and adhesive behavior, confirming a profound influence of cell density. These findings demonstrate for the first time that, under shear flow, adhesion of different density SS cells to the endothelium is dependent on the inverse of cell density rather than any changes in their adhesion potential. Finally, the trapping of ISC-rich native dense cells, but not of dehydrated discocytes, in the areas of adhesion shows a distinct contribution of ISC in adhesion-initiated vasoocclusion.

Adult↗
PubMed1994

Preliminary application of color Doppler flow imaging in the localization of parathyroid adenomas.

From December 1991 to April 1993, we performed color Doppler flow imaging (CDFI) in 11 patients with parathyroid adenoma, and all cases were confirmed by operation and pathology. In all the parathyroid adenomas, vessels were clearly revealed at the periphery of the upper pole and/or anterior periphery, where arterial signals were elicited. These arteries had branches into the adenomas and originated from inferior thyroid arteries on the same side in most cases. The internal flow signals were increased markedly as compared to normal thyroid, and high-velocity arterial signals were detected. Because of the thyroid's rich blood supply and landmark peripheral vessels, CDFI can distinguish parathyroid foci from thyroid nodules, lymph nodes, and normal tissues and provide a sound basis for the diagnosis of small parathyroid foci.

Adenoma↗
PubMed1994

[Construction of microfluorometer and its application for measuring intracellular free calcium].

A microfluorometer used for measuring intracellular free calcium has been constructed. This system was based on an XSJ-2 epifluorescence microscope with the following modifications. First, the AC mercury lamp was replaced by a DC xenon lamp to provide a stable light source. Second, an excitation filter wheel incorporating two interference filters was inserted in the light path allowing the biological sample to be excited alternately by lights of two different wavelength. The running of the whole system was under the control of a microcomputer. Such a system has successfully been used to monitor intracellular calcium changes with fluorescent calcium-sensitive dye Fura-2. Some examples of application are presented.

Animals↗
PubMed1994

[Radioimmunoimaging assay of ovarian tumor with 99mTc labeled anti-carcinoembryonic antigen monoclonal antibody].

Radioimmunoimaging (RI I) assay with 99mTc labeled anti-CEA monoclonal antibody was performed in 31 patients with suspected primary or recurrent malignant ovarian tumor. The radiation dose raging from 920MBq to 110MBq(1mgIgG) was administered i.v. for each patient. Anterior-posterior views of the pelvis and abdomen were obtained routinely with gamma-camera during 18-24 hour after the application of antibody. The results of RII were compared with the findings in operation or CT examination. Sensitivity in diagnosis was 100% (13/13), specificity was 94%(16/17) and metastatic foci sensitivity was 63%(10/16). The serum CA125 in this study appeared to be correlated with the results of RII. However, in 2 patients with normal serum CA125 titers RII revealed true positive. The preliminary clinical results of RII with 99mTc-MAb showed that RII is a promising method for the detection of malignant ovarian tumors.

Adolescent↗
PubMed1990

HSV (type 1) infection of the trigeminal complex.

Following corneal inoculation with herpes simplex virus (Type 1) (HSV), virus spreads to the CNS by axonal transport in the central branches of trigeminal ganglion cell neurons. Although this mode of viral entry to the CNS is rare for humans, it appears to be the principal route of entry into the CNS in animal models of herpetic corneal disease. In this study, the corneas of BALB/c mice were unilaterally inoculated with HSV, and the distribution of HSV-immunoreactive label was studied to identify the central branches of the axons of infected trigeminal ganglion cells. Virus was first noted in the brainstem trigeminal complex 4 days after corneal inoculation, when HSV-labeled afferents were found throughout the course of the descending tract of V as well as in interstitial neurons in the tract. By 5 days labeled neurons were also found not only in the n. caudalis and portions of the n. interpolaris of the trigeminal complex but also in laminae I-IV of the dorsal horn of the upper cervical levels of the spinal cord. No immunoreactivity was seen in other regions of the complex, including the n. oralis or the main sensory n. of V. By 6 days, however, the infection had spread to the main sensory division of V.

Animals↗
PubMed1990

Attenuation of opioid receptor activity by phorbol esters in neuroblastoma x glioma NG108-15 hybrid cells.

Chronic opioid treatment of neuroblastoma x glioma NG108-15 cells induces desensitization of the opioid receptor and this may involve a change in membrane protein phosphorylation. In an attempt to mimic this possible mechanism, we studied effects of phorbol ester activation of protein kinase C on opioid receptor activity. Incubation of NG108-15 hybrid cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) abolished up to 45% of opioid inhibition of cyclic AMP accumulation in intact cells, while basal accumulation and prostaglandin E1-stimulated cyclic AMP accumulation were unaltered. This decrease of opioid inhibition was dose- and time-dependent and the potency order of phorbol esters and apparent K activation (90 nM) for TPA were consistent with phorbol esters acting through the stimulation of protein kinase C. TPA also decreased the inhibition of cyclic AMP accumulation mediated through muscarinic and alpha-2 adrenergic receptors. These effects of TPA were best explained by a TPA-induced alteration of the inhibitory nucleotide-binding protein (Gi), the common transducer protein of these receptors. Impairment of Gi by TPA treatment was evidenced by a reduction in agonist-stimulated GTP hydrolysis and activation by GTP. Quantification of Gi by pertussis toxin-catalyzed ADP-ribosylation revealed that TPA decreased maximal labeling. In summary, phorbol esters appeared to attenuate opioid receptor activity by altering the activity of the transducer protein Gi.

Adenosine Diphosphate Ribose↗