Nuclear dependence of dimuon production at 800 GeV.
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Journal Article↗
Biomedical subjects
C Lee
Publications and source records attributed to C Lee.
Persistent photoconductivity in compensated amorphous silicon.
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Journal Article↗
Supermatrix proper-time representation of one-loop effective action and gauge invariance.
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Journal Article↗
Detection of hepatitis C viral sequences in non-A, non-B hepatitis.
The role of hepatitis C virus (HCV) in post-transfusion non-A, non-B hepatitis (NANBH) was investigated by analysing clinical samples for both HCV RNA by cDNA/polymerase chain reaction and antibodies against C100-3 by radioimmunoassay. Of fifteen chronic NANBH patients and one patient with chronic cryptogenic liver disease, ten were positive for anti-C100-3 and seven of the ten had viral sequences in their livers. However, two patients negative for anti-C100-3 also had substantial levels of HCV RNA in their livers. In acute post-transfusion NANBH (one surgical patient and two experimentally infected chimpanzees), HCV RNA was detected in the absence of anti-C100-3. In addition, infectious plasma from a seronegative patient with acute post-transfusion NANBH and a seronegative pool of plasma from a chimpanzee with chronic post-transfusion NANBH had high levels of HCV. These findings show that anti-C100-3-positive patients with chronic post-transfusion NANBH are likely to be viraemic; confirm that antibodies to C100-3 are a marker for infectivity; and suggest that the prevalence of HCV infections may be underestimated from the frequency of antibodies to C100-3 alone.
Animals↗
Non-androgenic role of testis in enhancing ventral prostate growth in rats.
This study was conducted to investigate whether the testis, aside from its ability to secrete androgen, is able to promote prostatic growth in rats. Increasing quantities of silastic capsules filled with crystalline dihydrotestosterone (DHT) were implanted subcutaneously into adult Sprague-Dawley rats at the time of bilateral epididymo-orchiectomy or sham operation on the testes. Control animals received empty capsules. Twenty-eight days later, the growth of the ventral prostate as measured by wet weight, DNA, and protein content per prostate was significantly greater in rats with intact testes than in orchiectomized rats. An overall increased growth was noted at all doses of exogenous DHT administered. Serum levels of luteinizing hormone in animals treated with DHT were undetectable. Serum levels of testosterone in intact rats treated with DHT were not significantly different from those in castrated rats. These observations suggest a non-androgenic role for the testis and, perhaps, epididymis in promoting prostatic growth in rats, and are consistent with the concept that a non-androgenic substance, produced from the testis and/or epididymis, is able to enhance prostate growth induced by androgen stimulation. The possibility that this phenomenon may play a role in the benign growth of the prostate observed in aging human males with decreased blood levels of androgen warrants consideration.
Analysis of Variance↗
Characterization of castration-induced cell death in the rat prostate by immunohistochemical localization of cathepsin D.
Activities of cathepsin D (EC 3.4.23.5) were determined in three lobes of the prostate during their involution by both biochemical and immunohistochemical procedures. The activity of cathepsin D in noncastrated rats was 0.9 +/- 0.2 (mean +/- SE) 5.7 +/- 0.6, and 13.1 +/- 0.8 units/mg protein for the ventral, lateral, dorsal lobes, respectively. Following castration, there was a significant increase in enzymatic activity in all three lobes within 2-3 days. In the ventral lobe, the activity peaked in 5 days to 6.2 +/- 0.9 units/mg protein and declined slightly thereafter. In the lateral and dorsal lobes, the activity remained elevated (14-20 units/mg protein) throughout the postcastration period studied. Immunohistochemical staining of cathepsin D was localized in the cytoplasm of prostatic epithelial cells as fine discrete lysosomal granules. These granules were larger and more abundant in the dorsal and lateral lobes than in the ventral lobe and were not detected in prostatic stromal cells and seldom in the luminal fluid. Castration resulted in an immediate increase in the size and number of these granules in the epithelial cells, followed by a sudden further increase in cathepsin D staining in some but not all epithelial cells. Lysosomal granules gradually coalesced in these cells to form large vacuoles that fit the characteristic description of apoptotic bodies. Finally, after day 7 postcastration, collapse and disintegration of the entire glandular structure was noted. Using this procedure to localize cathepsin D as a tool, we were able to follow the morphological events of prostatic cell death during castration-induced involution in the rat at the light microscopic level.
Analysis of Variance↗
Functional consequences of phospholipase A2 activation in human monocytes.
Human monocytes release arachidonic acid upon stimulation with a variety of soluble or particulate agents. These include: phorbol esters (i.e., 12-O-tetradecanoate phorbol-13-acetate, TPA), calcium ionophores (ionomycin), serum-treated zymosan (STZ) concanavalin A (Con A), and, to a minor degree, lipopolysaccharides (LPS). Protein Kinase C activation or increased intracellular Ca2+ are common features of the actions of most, if not all, of these stimuli. Prevention of PKC activation by the use of staurosporine or chelation of extracellular calcium by EGTA selectively impaired AA release, indicating that PLA2 may be regulated by either pathway concurrently. The generation of inositol phosphates and diacylglycerol by the action of phospholipase C, notably upon interaction with opsonized particles during phagocytosis, apparently constitutes the physiological correlate of stimulation via these agents. Release of arachidonic acid by the action of PLA2 or other phospholipid hydrolyzing enzymes leads directly to the formation of cyclooxygenase products. In the presence of markedly elevated calcium concentrations, 5-lipoxygenase (LO) is activated as well, leading to the formation and release of leukotrienes. Agents which stimulate AA release also initiate other monocyte functions, including generation of reactive oxygen intermediates and lymphokine release. This observation makes it tempting to implicate PLA2 activation in many aspects of monocyte physiology. However, no correlation with PLA2 activation and either superoxide or lymphokine release was found when multiple stimuli, including TPA, ionomycin, serum-treated zymosan, concanavalin A, or LPS, were compared simultaneously. Instead, our results indicate that PLA2 activation is regulated by the same mechanisms, including PKC activation and increased Ca2+, as are other enzymes which determine expression of monocyte function. Phospholipase A2 (PLA2) hydrolyzes fatty acid from the sn-2 position of a wide variety of phospholipids. Substrates for this (these) enzyme(s) include species which contain a variety of polar head groups (choline, serine, ethanolamine, etc.) and some phospholipids with either linkages in sn-1. In many cell types, including human monocytes, phospholipase A2 commonly acts on substrates containing arachidonic acid (AA). The liberation of free arachidonate is a first step in the metabolism of prostaglandins, hydroxyeicosatetraeinoic acids, (HETE'S), and leukotrienes (Lt's). Monocytes and macrophages have been shown to be rich sources of arachidonate and its metabolites. Some biologic properties of monocytes, notably their role as immunomodulating cells, have been attributed to eicosanoid production and release. Accordingly, much of the interest regarding PLA2 in human monocytes centers on this aspect of their function.(ABSTRACT TRUNCATED AT 400 WORDS)
Arachidonic Acid↗
Metabolic consequences of reduced frequency breathing during submaximal exercise at moderate altitude.
The intention of this study was to determine the metabolic consequences of reduced frequency breathing (RFB) at total lung capacity (TLC) in competitive cyclists during submaximal exercise at moderate altitude (1520 m; barometric pressure, PB = 84.6 kPa; 635 mm Hg). Nine trained males performed an RFB exercise test (10 breaths.min-1) and a normal breathing exercise test at 75-85% of the ventilatory threshold intensity for 6 min on separate days. RFB exercise induced significant (P less than 0.05) decreases in ventilation (VE), carbon dioxide production (VCO2), respiratory exchange ratio (RER), ventilatory equivalent for O2 consumption (VE/VO2), arterial O2 saturation and increases in heart rate and venous lactate concentration, while maintaining a similar O2 consumption (VO2). During recovery from RFB exercise (spontaneous breathing) a significant (P less than 0.05) decreases in blood pH was detected along with increases in VE, VO2, VCO2, RER, and venous partial pressure of carbon dioxide. The results indicate that voluntary hypoventilation at TLC, during submaximal cycling exercise at moderate altitude, elicits systemic hypercapnia, arterial hypoxemia, tissue hypoxia and acidosis. These data suggest that RFB exercise at moderate altitude causes an increase in energy production from glycolytic pathways above that which occurs with normal breathing.
Adult↗
Behaviors, beliefs, and intentions in skin cancer prevention.
This study investigated knowledge, behaviors, and health beliefs of Australian university students (n = 312) regarding skin cancers and evaluated the effects of videotaped presentations. Students' knowledge and health beliefs were assessed, and they then viewed either an informational video, an emotionally involving video, or a control video. Knowledge and beliefs were assessed immediately and 10 weeks later. Postvideo skin protection intentions increased significantly from prevideo assessment among the two intervention groups compared to the controls. Maintenance of skin protection intentions was higher with the emotional video. Health belief variables, particularly perceived barriers, were significant predictors of knowledge, intention, and behavior. However, other variables such as skin type and previous experience with skin cancer were more important. Females had greater knowledge and stronger intentions to prevent skin cancer than males but reported fewer high-risk behaviors.
Adult↗
Antinociceptive effects of elevated plus-maze exposure: influence of opiate receptor manipulations.
It has been suggested that anxiety may be a critical factor in certain forms of non-opioid environmental analgesia. In the present study, 5-min exposure to the elevated plus-maze test of anxiety (EPM) induced a mild, though enduring, elevation in tail-flick latencies in male mice. Pretreatment with the opiate antagonist naltrexone (0.1-10.0 mg/kg) failed to block EPM-induced antinociception: indeed, the highest dose actually enhanced the response. This effect could not be attributed to intrinsic analgetic activity of naltrexone. Rather, analysis of EPM behaviours suggested that it may have been secondary to an anxiogenic effect of the compound. The involvement of non-opioid substrates in the form of pain inhibition was further supported by the failure of chronic morphine treatment (7 days; 7.5 mg/kg) to alter either the antinociceptive or behavioural response to EPM exposure. Irrespective of treatment history, mice showed a retest EPM profile of enhanced anxiety, with tail-flick data suggesting a major contribution of anticipatory factors. Several important methodological variables are discussed and findings are contrasted with parallel studies on non-opioid defeat analgesia.
Animals↗
Vascular malformations and pregnancy.
Between January 1975 and June 1989, 240 patients with cerebral vascular malformations were treated at Henry Ford Hospital. In 16 of the patients, the treatment was influenced by pregnancy. Eleven of the patients presented with hemorrhage, four with seizures, and one with hydrocephalus. There were no maternal or fetal deaths in the patients presenting with seizure or hydrocephalus. There were two maternal deaths and one fetal death among the cases presenting with hemorrhage. In the patients with seizure or hydrocephalus, the pregnancy was brought to term and obstetric indications used to determine the time and method of delivery. Hydrocephalus was treated by shunting, and seizures with medication. Antiepileptic drug levels fluctuate in pregnancy and hence were closely monitored to ensure therapeutic levels. Vascular malformations are the most common cause of subarachnoid hemorrhage in pregnancy. The risk of rebleed in the same pregnancy is about 27%. If an arteriovenous malformation ruptures during pregnancy and the patient's condition deteriorates, appropriate emergency surgery should be done. In stable patients, our policy has been to bring the pregnancy to term and then electively perform a craniotomy to excise the arteriovenous malformation.
Adolescent↗
Repeat cerebral pan-angiography in subarachnoid hemorrhage of unknown etiology.
Cerebral pan-angiography was repeated in 24 patients with spontaneous subarachnoid hemorrhage confirmed by spinal fluid or computed tomography evidence after the initial pan-angiography was negative. Recent, long-term follow-up was also conducted. The pan-angiography was technically adequate and did not show vasospasm, both being causes of aneurysmal nonvisualization. No etiology was demonstrated on repeat study in all 24 patients. An additional three patients had only one study, but autopsy later confirmed lack of etiology for subarachnoid hemorrhage despite gross and microscopic serial sections. The mean duration of follow-up was 18.1 years and outcome was favorable. Our results suggest that repeat cerebral pan-angiography may not be indicated in the patient who has no further bleeding episodes and in whom the initial study was normal, technically adequate, and complete without evidence of vasospasm. Nonvisualization of a cerebral aneurysm is commonly proposed as the most likely cause of subarachnoid hemorrhage when angiography is normal following nontraumatic subarachnoid hemorrhage. Our results suggest this conclusion is no longer accurate if the angiogram is technically adequate with the absence of vasospasm.
Cerebral Angiography↗
Cloning of a cDNA for a T cell produced molecule with a putative immune regulatory role.
An expression cDNA library was constructed from the helper T cell hybridoma, A.1.1, which has been shown to produce constitutively proteins involved in the down regulation of the immune response. From this library we identified and characterized a cDNA clone, J6B7, by screening with a polyclonal antibody specific for secreted immune regulatory proteins. The mRNA for J6B7 is expressed specifically in some T cells, but not in the thymoma BW5147 or liver cells. J6B7 is 2937 nucleotides in length and contains one open reading frame encoding for a peptide of predicted Mr of 98,042. The nucleotide and deduced amino acid sequences of J6B7 did not reveal significant homology to any published sequences. Hybridization and translation experiments reveal that the J6B7 can hybrid select mRNA from total RNA isolated from either A.1.1 cells or thymic tissue which can be translated in vitro to a peptide which is bound by a monoclonal antibody (mAb) specific for antigenic determinant(s) shared by immune regulatory proteins. Furthermore, the in vitro translated proteins obtained from A.1.1 cells and thymus showed significant suppression of a mixed lymphocyte reaction (MLR) in a dose dependent manner, reaching maximum suppression of 71% and 89%, respectively. These results suggest that the cDNA, J6B7, codes for an immune regulatory protein.
Amino Acid Sequence↗
Chronic nicotine and withdrawal effects on radial-arm maze performance in rats.
Rats were tested for choice accuracy in an eight-arm radial maze during and after chronic administration of nicotine via subcutaneously implanted glass and Silastic capsules. Nicotine administration significantly improved choice accuracy relative to controls. The effect gradually became apparent over the first 2 weeks of exposure and persisted through the third week. Surprisingly, the significant facilitation of the nicotine-treated rats relative to controls continued for 2 weeks after the end of nicotine administration. No effects of nicotine were seen on choice latency or the strategy to make adjacent arm entries.
Animals↗
Proteins of the rat prostate. III. Effect of testosterone on protein synthesis by the ventral prostate of castrated rats.
Protein synthetic activities in the ventral prostate were assessed by two-dimensional electrophoresis in either four-day or seven-day castrated rats at different intervals following subcutaneous implantation of testosterone-filled silastic tubings for a period of up to four days. Prostatic tissues were cut into one to two mm. pieces and incubated in tissue culture medium containing S35-methionine (100 microCi/ml.) at 37C under 95% oxygen and 5% carbon dioxide for four hours. The incubated tissues were subjected to two-dimensional electrophoresis and radiofluorography. Analysis of protein spots detected in the fluorograms by computer-assisted densitometry revealed temporal changes in the synthesis of individual proteins by the ventral prostate of castrated rats following androgen treatment. Changes in two groups of proteins were evaluated: castration-induced proteins and androgen-dependent proteins. The level of synthesis of three castration-induced proteins (spots G, H, and I) declined rapidly upon testosterone treatment and reached a non-detectable level for spots G and H and a low level of synthesis for spot I by three days following androgen treatment. Synthesis of androgen-dependent proteins (spots D, E, and F) was activated by testosterone treatment. However, the time interval required to activate the synthesis of these proteins is different. Synthesis of protein spot D (prostatic binding protein) was detected as soon as half hour after the treatment. Synthesis of spots E and F, on the other hand, was not activated until 24 and 48 hours after the treatment, respectively. These changes in patterns of protein synthesis represent the characteristics of cellular responses to testosterone stimulation by the regressed prostate.
Animals↗
Differential cytokeratin expression in normal, hyperplastic and malignant epithelial cells from human prostate.
Studies were undertaken to define the expression of cytokeratins in normal, hyperplastic and malignant epithelial cells from human prostate. Cytokeratin (CK) polypeptides, separated by two-dimensional electrophoresis, were identified by immunoblotting with CK-specific monoclonal antibodies. CK polypeptides 5, 7, 8, 15, 18 and 19 were identified in fresh normal and hyperplastic prostate. Expression of CK 15 has not been previously reported in human prostate. Analysis of central and peripheral zone tissues from human prostate did not reveal qualitative differences in CK expression between these areas. Epithelial cells harvested from fresh BPH tissue by percoll gradient centrifugation and propagated in vitro using selective culture techniques showed alterations in CK expression compared to intact human prostate. Specifically, CKs 6, 14, 16 and 17 were noted in cultured BPH epithelial cells but not fresh normal prostate or BPH tissue. Immunoblot analysis of the established prostate cancer cell lines PC3, DU145 and LNCAP showed expression of CKs 8 and 18 but not CKs 5, 7 and 15 which were observed in benign prostate. These studies further characterize CK expression in benign and malignant human prostate and provide insights which may be useful in differentiating normal, hyperplastic and malignant epithelial cells in the human prostate gland.
Adult↗
Elevated transferrin receptor content in human prostate cancer cell lines assessed in vitro and in vivo.
Transferrin receptors (TfR) were measured in benign and malignant prostatic cells by performing Scatchard analysis following the administration of 125I-transferrin. Established human prostate cancer cell lines (PC-3 and DU-145) as well as biologically aggressive variants (PC-3 ASC and PC-3 DES) were shown to possess significant levels of high affinity TfR when assessed in vitro. In contrast, TfR content was negligible in cultured stromal cell fractions derived from human benign prostatic hyperplasia (BPH) specimens. Scatchard analysis was also performed on in vivo derived prostatic tissues: tumors resulting from the subcutaneous xenografting of PC-3 ASC cells into athymic, nude mice and fresh BPH surgical specimens. These tissues were dissociated and their stromal and epithelial components separated. TfR were only detected in the epithelial component of both malignant and benign epithelial cells. PC-3 ASC tumor cells exhibited TfR levels comparable to their in vitro expression and these levels were 10-fold greater than in the BPH cells. These findings suggest that elevated TfRs may serve as another useful marker of the transformed phenotype within human prostate tumor systems.
Animals↗
Application of scanning electrochemical microscopy to biological samples.
The scanning electrochemical microscope can be used in the feedback mode in two-dimensional scans over biological substrates to obtain topographic information at the micrometer level. In this mode, the effect of distance between a substrate (either conductive or insulating) and a scanning ultramicroelectrode tip on the electrolytic current flowing at the tip is recorded as a function of the tip x-y position. Scans of the upper surface of a grass leaf and the lower surface of a Ligustrum sinensis leaf (which show open stomata structures) immersed in aqueous solution are shown. Scans of the upper surface of an elodea leaf in the dark and under irradiation, where the tip reaction is the reduction of oxygen produced by photosynthesis, demonstrate the possibility of obtaining information about the distribution of reaction sites on the substrate surface.
Electrochemistry↗