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Biomedical subjects

J Y Lei

Publications and source records attributed to J Y Lei.

10 recordsLinked to original sources
PubMed2001

Pigmented renal clear cell carcinoma with melanocytic differentiation.

Renal cell carcinoma (RCC) is the most common malignant tumor of the adult kidney, and its incidence has been steadily rising. RCC consists of several subtypes, each of which has its own clinical features, and cytogenetic and molecular characteristics. Recognizing histologic patterns of RCC is important not only for correct diagnosis, but also for providing insight into the biological behavior of the tumor and subsequent appropriate medical care for the patient. Pigments other than hemosiderin has been observed in RCC, but none of them have been proved to be melanin. Melanotic tumors, either primary or metastatic, are rare in the kidney. We present an unusual case of melanin-pigmented clear cell RCC with melanocytic differentiation, an unusual variant that may lead to errors in diagnosis and treatment.

Adenocarcinoma, Clear Cell↗
PubMed2000

Microcystic adnexal carcinoma associated with primary immunodeficiency, recurrent diffuse herpes simplex virus infection, and cutaneous T-cell lymphoma.

Cutaneous microcystic adnexal carcinoma (MAC) is a rare and poorly understood tumor that predominantly occurs in the head and neck. MAC usually affects people in their fourth and fifth decades. Some patients have had a history of radiation. We present a case of MAC occurring in the left antecubital fossa of an 18-year-old white woman with an unusual immunodeficiency syndrome. The patient also developed a squamous cell carcinoma, a cutaneous T-cell malignancy, and a perigastric leiomyoma. A congenital infection of herpes simplex virus (HSV) persisted throughout her life. The association of HSV infection with MAC and squamous cell carcinoma and that of peripheral T-cell lymphoma with Epstein-Barr virus is discussed in relation to her immunodeficiency.

Adolescent↗
PubMed2000

Biological effects of cementum and bone extracts on human periodontal fibroblasts.

BACKGROUND: Non-collagenous proteins of mineralized tissues play important roles in bone induction during mineralization and in regulating the activity of many types of mesenchymal cells. This study was conducted to determine the effects of acetic acid extracts of bone and cementum on alkaline phosphatase (ALPase) activity and in vitro mineralization of cultured human periodontal fibroblasts (hPF). METHODS: Alveolar bone and cementum obtained from clinically healthy subjects were extracted by a solution containing 0.5 M acetic acid and enzyme inhibitors. Osteoblastic phenotypes of hPF were assayed by ALPase activity, gene expression of bone marker proteins, and the ability to produce in vitro mineralization in culture media containing 50 microg/ml ascorbic acid, 10 mM sodium beta-glycerophosphate, and 10(-7) M dexamethasone. The effects of cementum and bone extracts on the expression of osteoblastic phenotypes in hPF were also determined. RESULTS: Many protein components, varying in molecular weight from 10 to 14 to 120 kDa, were detectable in 10% SDS-PAGE of both cementum and alveolar bone extracts. The hPF cells were found to exhibit a moderate ALPase activity when compared with rat osteosarcoma (ROS) 17/2.8 cells under the same experimental conditions. Gene expression for ALPase, osteocalcin bone sialoprotein, osteopontin, and BMP-7 at mRNA message was detected by RT-PCR in hPF and ROS 17/2.8 cells. The confluent hPF and ROS 17/2.8 cells showed evidence of calcium deposition in the extracellular milieu at 30 and 15 to 30 days' cultures, respectively, under a mineralization medium. The hPF appeared to form mineralized foci with morphological characteristics different from the mineralized nodules produced by ROS 17/2.8 cells. The addition of low concentrations (5 microg/ml) of either cementum or bone extract produced an increase in the size and number of mineralization spots, as well as greater ALPase activity in both hPF and ROS 17/2.8 cultures during the observation periods. CONCLUSIONS: These results suggest that hPF possess certain mineralizing phenotypes, and that acetic acid extracts of bone and cementum contain components capable of stimulating osteogenic differentiation of hPF.

Acetic Acid↗
PubMed2000

[Design of a infrared single-channel ECG telemetry system].

A single-channel ECG telemetry system with infrared rays as the medium was designed. It can be used to monitor the subject's ECG in real-time. This system has functions of detecting abnormal ECG, alarming, dieplaying, storing and printing. It is a beneficial attempt in the clinical application of the infrared telemetry.

Electrocardiography↗
PubMed1999

[Development of a multi-channel physiological telemetry system].

OBJECTIVE: To develop an instrument used in measurement of physiological parameters in laboratories or field. Method A: computer was used to process data in the telemetry system. The frequency-time division modulation technique was adopted. The low frequency signals were directly connected to the computer serial port after demodulation, and measurement control was achieved by single-chip computer. Temperature measurement results were obtained by conversion table. RESULT: It is capable of telemeter and processing ECG, wind speed and temperature signals in real-time. Good results were gained in high temperature condition and -17 degrees C environment. CONCLUSION: The instrument has many advantages, such as high accuracy, good processing ability, reliability, long operation distance, small volume and easy operation.

Aerospace Medicine↗
PubMed1995

Modulation of periodontal ligament fibroblasts by cementum and alveolar bone extracts.

This study investigated the effect of acetic acid extracted proteins of bone and cementum on periodontal ligament fibroblasts. Alveolar bone and cementum obtained from clinically healthy subjects were subjected to 0.5 M acetic acid extraction, dialysis and lyophilization. Effects of both extracts on cell attachment and stimulation of DNA synthesis were studied in fibroblast-like cells cultured from human periodontal ligament tissue. A wide spectrum of proteins, such as 11-14, 17, 19, 22, 24, 27, 30, 34-44, 47 and 55 kDa, were detected in 10% SDS-polyacrylamide gel electrophoresis of both extracts. A few tissue-specific bands (19, 22, 47 kDa in cementum extract; 34-44, 55 kDa in bone extract) were noted. These extracts were found to promote cell attachment and stimulate DNA synthesis of periodontal fibroblasts. Cementum extract appeared to have a higher activity in stimulating DNA synthesis than bone extract, while promotion of cell attachment was similar with both extracts. Addition of serum evoked a synergistic effect on the promotion of DNA synthesis of both extracts. These preliminary observations suggest that acetic acid extracts from bone and cementum contain distinct components capable of modulating cellular activities of periodontal fibroblasts.

Bone and Bones↗
PubMed1994

Insights into autoregulation from the crystal structure of twitchin kinase.

Many protein kinases are self-regulated by an intrasteric mechanism where part of the enzyme's structure directly inhibits the active site. This inhibitory structure is called a pseudosubstrate and specific regulators are required to remove it from the active site to allow substrates access. Removal of the pseudosubstrate sequence from members of the myosin light-chain kinase subfamily, including twitchin kinase, activates them but it is not known whether the pseudosubstrate sequence binds to the active site. Native twitchin is a 753K protein (6,839 residues) located in muscle A-bands of the nematode Caenorhabditis elegans and because of its size has not been easy to study. We have determined the crystal structure, refined to 2.8 A resolution, of a recombinant fragment (residues 5,890 to 6,262) of twitchin kinase that contains the catalytic core and a 60 residue carboxy-terminal tail. The C-terminal tail extends through the active site, wedged between the small and large lobes of the structure and making extensive contacts with the catalytic core which accounts for autoinhibition and provides direct support for the intrasteric mechanism of protein kinase regulation.

Amino Acid Sequence↗
PubMed1994

Crystallization and preliminary X-ray analysis of the auto-inhibited twitchin kinase.

An auto-inhibited fragment of twitchin kinase (residues 5890 to 6262) has been crystallized by vapor diffusion techniques using polyethylene glycol 4000 as the precipitant at pH 7.25 to 7.5 at 4 degrees C. We have found that MgSO4 and glycerol were essential for large crystal growth. The crystals belong to the orthorhombic space group P2(1)2(1)2, with unit cell dimensions of a = 144.1 A, b = 168.3 A and c = 60.6 A. They are suitable for X-ray analysis and diffract to a resolution of at least 2.8 A.

Animals↗