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J K Lee

Publications and source records attributed to J K Lee.

At least 19 recordsLinked to original sources
PubMed1992

Identification of cis- and trans-acting factors regulating the expression of the human insulin receptor gene.

The functional organization of the human insulin receptor (hIR) promoter was analyzed by deletion mutagenesis and protein-DNA interaction studies. A series of deletion mutants was expressed transiently in two human hepatocytes, HepG2 and PLC. The results revealed that the promoter region between -692 and -345 is essential for efficient transcription of the hIR gene. Multiple trans-acting factors were identified by band shift and footprinting analyses. Sp1 binds to a cluster of GC boxes and two GGGAGG hexamers locating at -637 to -594. Adjacent to GC boxes, there are two regions, from -550 to -530 and from -522 to -503, which bind to two novel factors, IRNF-I and IRNF-II. These two factors are distributed differentially in different cell lines. Linker scanning mutations on GC, GA boxes, or the IRNF-I binding site significantly decreased the transcriptional activity, indicating that IRNF-I and Sp1 are important for hIR promoter activity. In addition, we demonstrated that glucocorticoid-dependent transcriptional induction of hIR mRNA in vivo is conferred by a glucocorticoid response element in the hIR promoter. Taken together, these results imply that transcription of the human insulin receptor gene is regulated by multiple protein-DNA interactions occurring within the defined promoter region.

Animals↗
PubMed1992

Growth of human acoustic neuromas, neurofibromas and schwannomas in the subrenal capsule and sciatic nerve of the nude mouse.

To develop a reproducible in vivo model for the growth of human acoustic neuromas and neurofibromas, we implanted tumor specimens (6 acoustic neuromas; 4 neurofibromas; 3 schwannomas arising in skin and soft tissues) from 13 different patients into the subrenal capsules of 67 nude mice and sciatic nerves of 64 nude mide. The animals were anesthetized and the tumors were microscopically implanted. Serial tumor volumes were determined at intervals up to 2 months by reopening the incision and directly measuring the tumor size with a micrometer. The percentages of acoustic neuromas that survived or grew were 57.1% in the subrenal capsule and 88.9% in the sciatic nerves; the percentages of neurofibromas that survived and grew were 50% in the subrenal capsule and 70% in the sciatic nerves; and the percentages of schwannomas that survived and grew were 57.1% in the subrenal capsule and 94.1% in the sciatic nerve. Tumors in the sciatic nerve also survived and grew for a longer period than those in the subrenal capsules. Tumor enlargement and stability correlated with neovascularity. At 1 or 2 months after engraftment, the tumors showed histologic appearances similar to the original tumors and immunohistochemical analysis of cryostat sections demonstrated staining of the tumors, but not the host mouse tissues for human beta 2-microglobulin, a species-specific marker. Furthermore, analysis of genomic DNA from implanted tumors revealed its human origin. We conclude that human acoustic neuromas, neurofibromas and schwannomas are readily grown in two sites in nude mice and that they retain their morphologic features and genomic identities. These tumors grow better and more consistently in the sciatic nerve than in the subrenal capsule. These are useful model systems for studying tumor growth and cellular modulation.

Animals↗
PubMed1992

Detection of vincristine-induced hyperploidy in meiotic II metaphases of male Chinese hamsters.

Induction of hyperploidy in germ cells of male Chinese hamsters treated with vincristine at dose levels of 0.25, 0.50 or 0.75 mg/kg of body weight was investigated. Animals were killed at 6, 24, 48, 72 and 96 h after administration of the chemical by a single intraperitoneal injection. The testes were removed and processed for spermatogonial, meiotic I, and meiotic II metaphases. Significantly increased frequencies of hyperploidy were obtained in meiotic II cells harvested 6, 24 and 48 h but not 72 and 96 h after treatment, indicating the importance of multiple sampling times. Analysis of spermatogonial cells shows that the frequencies of hyperploidy in the treated samples were comparable to those of controls. Limited sampling times used in the present study as well as small sample size or possible loss of hyperploid cells may be responsible for the negative findings for spermatogonial cells. Examination of meiotic I cells from 53 animals reveals the presence of one animal with an elevated level of hyperploidy unrelated to the vincristine treatment.

Animals↗
PubMed1992

Proliferation and morphological transformation of BALB/3T3 cells by a prolonged treatment with sodium orthovanadate.

BALB/3T3 mouse embryo cells were used to study the effect of sodium orthovanadate on cell proliferation and morphological transformation. In the presence of the chemical (0.25-1.0 micrograms/ml), the cells continued to proliferate after the cultures were confluent. However, contact-inhibited growth was resumed after removal of the chemical from the culture medium. Continued exposure of the cells to the chemical for 4 wk led to the production of numerous foci consisting of morphologically transformed cells. In contrast, as in vitro transformation assay with a 48-hr treatment protocol followed by 4 wk of incubation without the chemical produced negative results. To test the stability of the transformed foci that were produced on prolonged exposure, we isolated 20 foci with distinctly transformed characteristics from treated cultures and grew them in medium without orthovanadate. 15 isolates gradually reverted to contact-inhibited growth and five maintained the transformed phenotype through ten serial subcultures. The results show that the majority of the transformed foci from the orthovanadate-treated culture failed to maintain transformed characteristics in the absence of the chemical. However, a small fraction of the foci appeared to be altered permanently and exhibited a transformed phenotype in the absence of the chemical.

3T3 Cells↗
PubMed1992

MR imaging of benign prostatic hypertrophy using a Helmholtz-type surface coil.

MR examinations of the prostate were performed on six healthy volunteers and 18 patients with well-documented symptomatic benign prostatic hypertrophy, using an organ-encompassing Helmholtz-type surface coil at 1.5 T. The healthy volunteers were also imaged with a standard circumferential body coil. The morphologic features and signal intensity characteristics of the prostate and adjacent structures were analyzed in the patient group. Several recognizable patterns of benign prostate hypertrophy were identified including bilaterally symmetrical nodules in the central gland, multiple central gland nodules, and a diffusely heterogeneous central gland without appreciable nodules. The peripheral zone was of moderate to high signal intensity on T2-weighted images, and was diffusely heterogeneous in 78% of patients. The false prostatic capsule, peripheral venous plexus, and seminal vesicles were also characterized. A good correlation was shown between prostatic glandular volume and prostate-specific antigen. Calculated signal-to-noise ratios (S/N) were significantly greater on images acquired with the Helmholtz-type receiver coil than on those acquired with the body coil. We conclude that the hyperplastic prostate gland has a variety of MR appearances, but that recognizable patterns are frequently seen. High resolution imaging with a Helmholtz-type surface coil provides excellent anatomical depiction of the prostate and adjacent structures.

Aged↗
PubMed1992

cis-acting regulatory elements involved in oxygen and light control of puc operon transcription in Rhodobacter sphaeroides.

Transcriptional expression of the puc operon in Rhodobacter sphaeroides is highly regulated by both oxygen and light. The approximately 600 bp of DNA upstream of the 5' ends of the two puc-specific transcripts encompasses two functionally separable cis-acting domains. The upstream regulatory region (URS) (-629 to -150) is responsible for enhanced transcriptional regulation of puc operon expression by oxygen and light. The more proximal upstream region (downstream regulatory region [DRS]), containing putative promoter(s), operator(s), and factor binding sites (-150 to -1), is involved in unenhanced transcriptional expression of the puc operon under aerobic and anaerobic conditions. Thus, the DRS shows normal derepression of puc operon expression when cells are shifted from aerobic to photosynthetic growth conditions in terms of percent change but does not show the potential range of expression that is only observed when elements of the URS are present. Because of these observations, we have made a distinction between anaerobic control (describing the shift) and oxygen control (describing the magnitude of derepression). Promoter(s) and/or activator function(s) of the puc operon is associated with a 35-bp DNA region between -92 and -57. Homologous sequences at -10 to -27 and -35 to -52 appear to involve additional regulatory elements: mutations at -12 (A to C) and -26 (G to A) result in partial derepression of puc operon expression under conditions of high aeration. Both point mutations require the upstream regulatory region (-629 to -150) to be present in cis for partial derepression of puc operon transcription under aerobic conditions. Immediately upstream of the promoter and/or activator region are overlapping consensus sequences for IHF (integratin host factor) and FNR (fumarate nitrate reductase) (-105 to -129). This region appears to be essential for enhanced expression of the puc operon. Thus, these two regulatory domains (URS and DRS) appear to involve approximately seven unique regulatory elements. In addition, the data reveal a direct interaction between the URS (-629 to -150) and the DRS (-150 to -1).

Anaerobiosis↗
PubMed1992

Isolation and characterization of trans-acting mutations involved in oxygen regulation of puc operon transcription in Rhodobacter sphaeroides.

Transcriptional expression of the puc operon in Rhodobacter sphaeroides 2.4.1 is dependent on the partial pressure of oxygen. By using transcriptional fusions in trans of a promoterless fragment derived from the aminoglycoside-3'-phosphotransferase gene of Tn903 to puc operon-specific DNA containing a 629-bp 5' cis-acting regulatory region involved in the expression of puc-specific mRNA, we selected Kmr colonies under aerobic conditions. Two broad classes of mutations, trans and cis, which are involved in O2 control of puc operon transcription, fall into several distinct phenotypic classes. The cis-acting regulatory mutations are characterized in detail elsewhere (J.K. Lee and S. Kaplan, J. Bacteriol. 174:1146-1157, 1992). Two trans-acting regulatory mutants, CL1a and T1a, which are B800-850- Car- and apparently B875-, respectively, were shown to derepress puc operon transcription in the presence of oxygen. The mutation giving rise to CL1a has been shown to act at the puc operon-specific cis-acting upstream regulatory region (-629 to -92). On the other hand, the mutation giving rise to T1a, identifying a second trans-acting regulatory factor(s), appears to act at both the upstream (-629 to -92) and the downstream (-92 to -1) regulatory regions of the puc operon as well as at the level(s) of bacteriochlorophyll and carotenoid biosyntheses, as revealed by the presence of the B800-850 complex under chemoheterotrophic growth conditions. Both the B800-850- Car- phenotype and the trans-acting effect on puc operon expression in mutant CL1a were complemented with a 2.2-kb DNA fragment located within the carotenoid gene cluster. Mutant T1a was complemented with a 7.0-kb EcoRI restriction fragment containing the puhA gene and its flanking DNA (6.3 kb) to restore expression of the B875 complex and to suppress the trans-acting effect resulting in the loss of 02 control. Under chemoheterotrophic conditions, mutant T1a was highly unstable, segregating into a PS- mutant designated T4.

Blotting, Northern↗
PubMed1992

Hepatic MR imaging with Mn-DPDP: safety, image quality, and sensitivity.

Ninety-six patients with known or suspected focal hepatic disease were evaluated in a multiinstitutional study of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'bis(phosphate) (DPDP) as a hepatic-specific contrast agent for magnetic resonance (MR) imaging. The patients were divided into four dose groups, receiving 3, 5, 8, or 10 mol/kg of Mn-DPDP. Half of the patients in each dose group received Mn-DPDP as an intravenous bolus (0.25 mL/sec) and the other half as an infusion (1 mL/min). Patients were evaluated with T1-weighted imaging parameters. No serious side effects were noted. In 76 patients, both Mn-DPDP-enhanced and nonenhanced T1-weighted images depicted the same number of lesions, but one additional lesion was depicted with enhanced imaging in 12 patients, two additional lesions in three patients, and three additional lesions in three patients. Enhanced, T1-weighted images depicted no more lesions than nonenhanced, T2-weighted images in 77 patients, but one more lesion was depicted in nine patients, two more lesions in two patients, three more lesions in one patient, and four more lesions in one patient.

Adolescent↗
PubMed1992

MR appearance of the normal and abnormal vagina after hysterectomy.

To define the MR appearance of the vagina after hysterectomy, we reviewed the MR examinations of 43 women who had undergone hysterectomy for a variety of benign and malignant indications. In eight of the patients, MR examinations showed a mass lesion involving the vagina. The masses included four recurrent primary gynecologic malignant neoplasms (one endometrial, one ovarian, and two cervical carcinomas) and four primary vaginal carcinomas. The remaining 35 patients had no evidence of vaginal disease. Of these 35 patients, the repaired vaginal apex, or vaginal cuff, was linear and smooth in appearance in 23 and partially obscured by surgical clip artifacts in seven. In the other five patients, the vaginal cuff had a nodular appearance that was indistinguishable from a vaginal mass on T1-weighted images. However, the vagina had a normal appearance in these patients on T2-weighted images, on which the low-signal-intensity layer of vaginal smooth muscle could be distinguished from the bright outer layer of connective tissue. In patients with recurrent vaginal tumors, the tumor was relatively high in signal intensity on T2-weighted images and obliterated the low-signal-intensity vaginal muscularis. Our experience shows that the normal posthysterectomy vagina may have a nodular appearance on T1-weighted images mimicking a vaginal mass. This appearance can be distinguished from that of a true vaginal mass on the basis of different signal intensity characteristics on T2-weighted images.

Adult↗
PubMed1992

Arthroscopic capsular suture for anterior instability of the shoulder.

We assessed the results of arthroscopic transglenoid capsular suture in eight recurrent traumatic unidirectional anterior dislocations. At an average follow up of 11 months, ranging from eight to 18 months, assessment by Rowe's scoring system were excellent or good in all shoulders. There were no redislocations and all patients achieved near full, painless range of motion. There were no complications. We propose a new classification of anterior capsular lesions (Bankart lesion) and we describe the details of the arthroscopic suture technique. We conclude that arthroscopic suture is an effective method with low surgical morbidity and low cost in the treatment of recurrent anterior dislocation of the shoulder.

Adolescent↗
PubMed1991

Liver imaging at 1.5 tesla: pulse sequence optimization based on improved measurement of tissue relaxation times.

In order to predict the most sensitive MR imaging sequence for detecting liver metastases at 1.5 T, in vivo measurements of T1 and T2 relaxation times and proton density were obtained using multipoint techniques. Based on these measurements, two-dimensional contrast contour plots were constructed demonstrating signal intensity contrast between hepatic lesions and surrounding liver parenchyma for different pulse sequences and pulse timing parameters. The data predict that inversion recovery spin echo (IRSE) imaging should yield the greatest contrast between liver metastases and liver parenchyma at 1.5 T, followed by short tau inversion recovery (STIR) and spin-echo (SE) pulse sequences. T2-weighted SE images provided greater liver/lesion contrast than T1-weighted SE pulse sequences. Calculated T1, T2, and proton density values of the spleen were similar to those of hepatic metastatic lesions, indicating that the signal intensity of the spleen may be used as an internal standard to predict the signal intensity of hepatic metastases on T1- and T2-weighted images at 1.5 T.

Adult↗
PubMed1991

Bacillus licheniformis APase I gene promoter: a strong well-regulated promoter in B. subtilis.

The 5' regulatory region and the portion of the structural gene coding for the amino-terminal sequence of alkaline phosphatase I (APase I) were isolated from Bacillus licheniformis MC14 using a synthetic oligodeoxynucleotide deduced from the amino acid sequence of the enzyme. The DNA sequence analysis of this region revealed an open reading frame of 129 amino acids containing the amino-terminal sequence of the mature APase protein. The protein sequence was preceded by a putative signal sequence of 32 amino acid residues. The predicted amino acid sequence of the partial APase clone as well as the experimentally determined amino acid sequence of the enzyme indicated that B. licheniformis APase retains the important features conserved among other APases of Bacillus subtilis, Escherichia coli, Saccharomyces cerevisiae, and various human tissues. Heterologous expression studies of the promoter using a fusion with the lacZ gene indicated that it functions as a very strong inducible promoter in B. subtilis that is tightly regulated by phosphate concentration.

Alkaline Phosphatase↗
PubMed1991

Tibial collateral ligament bursa: MR imaging.

The bursa of the tibial collateral ligament (TCL) may be visualized at magnetic resonance (MR) imaging when it becomes distended with fluid. In the authors' experience, this finding signifies a pathologic condition either in the medial capsuloligamentous complex or in the bursa itself. Such a finding may indicate TCL bursitis. TCL bursitis can be suspected in the setting of isolated pain in the medial joint line in the absence of mechanical symptoms. Prolonged relief of symptoms after injection of steroid into the bursa is supportive of the diagnosis. Seven cases are presented in which a fluid-filled TCL bursa was identified at MR imaging. In five cases, TCL bursitis was suspected. The differential diagnosis for the MR findings is discussed.

Adult↗
PubMed1991

Renal transplants: can acute rejection and acute tubular necrosis be differentiated with MR imaging?

Magnetic resonance (MR) imaging was used in 40 renal transplant recipients to determine whether this modality can enable distinction of acute tubular necrosis (ATN) and acute rejection by means of corticomedullary differentiation (CMD). Each patient underwent initial MR imaging after allograft renal transplantation. Twenty-nine of these 40 patients (72%) also underwent subsequent follow-up MR imaging. Seventeen studies were obtained during episodes of ATN; 12 of these studies (71%) showed poor CMD. Eleven studies were obtained during episodes of acute rejection; eight of these studies (73%) showed poor CMD. In addition, six of seven studies (86%) showing various combinations of renal disease (ATN, acute rejection, chronic rejection, and cyclosporine toxicity) also showed poor CMD. Loss of CMD is reversible after improvement of ATN and acute rejection. Because loss of CMD is a nonspecific though sensitive sign reflecting renal transplant dysfunction, MR imaging is of limited value in the differentiation of ATN from acute rejection.

Acute Disease↗
PubMed1991

Dynamic gadolinium-enhanced rapid acquisition spin-echo MR imaging of the liver.

Rapid acquisition spin-echo (RASE) magnetic resonance (MR) imaging allows for coverage of the entire liver with highly T1-weighted SE images during a single 23-second breath-holding period. The RASE sequence was implemented in conjunction with rapid intravenous injection of gadopentetate dimeglumine to enable performance of dynamic contrast material-enhanced MR imaging of the liver. Prospective evaluation of 24 patients with 62 liver lesions 1 cm or greater in diameter was performed. Images obtained with RASE were devoid of respiratory-related ghost artifacts or edge blurring. The dynamic contrast-enhanced RASE technique resulted in contrast-to-noise and contrast-to-artifact values and time efficiency measures significantly greater (P less than .05) than those obtained with use of conventional T1- and T2-weighted pulse sequences, indicating a higher likelihood for lesion detectability. Lesion conspicuity was maximal during or immediately following bolus administration of gadopentetate dimeglumine, with lesions often becoming obscured at delayed postcontrast imaging.

Adult↗
PubMed1991

Focal hepatic lesions: differentiation with MR imaging at 0.5 T.

Magnetic resonance (MR) examinations of 43 patients with 95 focal hepatic lesions (diameter, greater than 1 cm) were analyzed for lesion shape, homogeneity, and relative signal intensity compared with normal liver parenchyma, spleen, and skeletal muscle. On T1-weighted, balanced, and T2-weighted images, most metastases (74%), cavernous hemangiomas (76%), and cysts (82%) were smooth and round or oval, while the hepatocellular carcinomas all had irregular borders (40%) or were lobulated (60%). All lesions with irregular borders were malignant. Seventy percent of metastatic lesions, 85% of cavernous hemangiomas, and 100% of simple hepatic cysts were of homogeneous signal intensity, while 60% of hepatocellular carcinomas were inhomogeneous. Logistic regression analysis of multiple lesion characteristics showed that inhomogeneous lesions had a high likelihood of malignancy, while markedly hyperintense lesions had a very low probability of being malignant, regardless of other traits. Homogeneous lesions that were isointense or hyperintense compared with spleen on balanced images but were not markedly hyperintense on T2-weighted images also had a high likelihood of malignancy.

Adult↗