Elevated vascular endothelial growth factor levels in the vitreous of patients with proliferative diabetic retinopathy

OBJECTIVE

To detect the levels of vascular endothelial growth factor (VEGF) in the vitreous of patients with proliferative diabetic retinopathy (PDR) and to investigate the possible role of VEGF in the development of neovascularization in PDR.

METHODS

Undiluted vitreous samples and fasting venous blood samples were obtained from 27 patients with PDR and 14 subjects with idiopathic macular hole who underwent pars plana vitrectomy. The concentration of VEGF was determined by quantitative enzyme-linked immunosorbent assay (ELISA).

RESULTS

The level of vitreous VEGF in patients with PDR (median 0.41 ng/ml, range 0.09-11.56 ng/ml) was significantly elevated when compared with that in control subjects (median 0.017 ng/ml, range 0.008-0.04 ng/ml) (P < 0.001). The median of PDR patients' serum VEGF concentration was 0.19 ng/ml (0.090.46 ng/ml) which was far lower than vitreous VEGF concentration (P < 0.05). Vitreous VEGF concentration was higher in PDR patients with retinal detachment than that in patient without retinal detachment (P < 0.05).

CONCLUSIONS

Vitreous levels of VEGF were remarkably elevated in eyes with PDR, and they were not influenced by its serum concentrations. VEGF played an important role in neovascularization of PDR.

Fast reversible electron transfer for photosynthetic reaction center from wild type Rhodobacter sphaeroides re-constituted in polycation sandwiched monolayer film

Direct reversible electron transfer for photosynthetic reaction center from wild type Rhodobacter sphaeroides re-constituted in polycation sandwiched monolayer film was observed in this work. The redox potential E0' = 0.46 V vs. NHE for first primary donor redox couple P/P+ was accurately measured from reversible CV or SWV peaks, which were quite close to those obtained from optic redox titration method. Reaction center (RC) in film was found re-constituted in such an ordered way that the orientation of RC favored the electron transfer in film. Thus, the protein electroactivity seems to be turned on in this artificial biomimic thin film. Furthermore, RC in the film features a photo-induced redox-peak fluctuation, suggesting an intact and functional state for RC in such film. Redox peaks were also found dependent of pH, implying a proton-coupled electron transfer occurring in film. Charge recombination was observed accompanied with change of electrochemical driving force. Electrochemical model assuming several classes of electroactive sites in the films on the electrode with a dispersion of standard potentials successfully fits SWV experimental data at different pulse height and frequency.

[Cloning and sequencing of cDNA from G protein gene of subgroup B respiratory syncytial virus strain isolated in China]

The nucleotide sequence of the G protein gene of respiratory syncytial virus (RSV) CC169 strain isolated from China that has been identified as subgroup B with monoclonal antibodies, was determined from cDNA that had been amplified by RT-PCR and cloned into pTZ18R plasmid vector. The homology of nucleotide was 94% as compared with G protein cDNA of a RSV prototype strain (CH18537). Deduced amino acid identity of G protein was 89.4%. The amino acid changes were only in the extracellular part of the protein where there were two extensive divergent domains with a highly conserved region in between; whereas the cytoplasmic and transmembrane domains were conserved. This study demonstrates the sequence diversity of the G protein of subgroup B RSV between a Chinese isolate and the prototype strain CH18537.

A novel pineal night-specific ATPase encoded by the Wilson disease gene

We have identified a pineal night-specific ATPase (PINA), a novel splice variant of the ATP7B gene disrupted in Wilson disease (WD). PINA expression exhibits a dramatic diurnal rhythm in both pineal gland and retina with 100-fold greater expression at night than at day. PINA is expressed in pinealocytes and a subset of photoreceptors in adult rats and is transiently expressed in the retinal pigment epithelium and the ciliary body during retinal development. Nocturnal pineal expression of PINA is under the control of a suprachiasmatic nucleus clock mediated by superior cervical ganglion innervation of the pineal. In vitro, PINA expression in pineal cells can be stimulated by agents activating the cAMP signal transduction pathway. PINA is able to restore copper transport activity in Saccharomyces cerevisiae deficient in the homologous copper-transporting ATPase CCC2, suggesting that this protein may function as a copper transporter in rat pinealocytes. These studies suggest a potential role of rhythmic copper metabolism in pineal and/or retina circadian function.

[The application of intracoronary stenting to type B and C lesions of coronary arteries]

Intracoronary stenting was introduced to 4 lesions due to coronary arterial dissections and to 2 lesions owing to elastic recoil of coronary arteries and stent placement was directly performed in 6 complex coronary lesions after 12 target lesions from 7 patients with Types B and C lesions of coronary arteries had been pre-dilated with balloon. Coronary angiography showed that dissections and recoils had disappeared. Target lesions were well dilated and blood flow was well improved in all cases, one patient was complicated with hemorrhage which was cured quickly. During the follow-up period of 1 to 24 months, another case had recurrence of angina after 2 months of stenting which could be controlled with anti-angina agents. These indicate that intracoronary stenting had good therapeutic effect and is considered as a safe, fast and effective method in dealing with acute complications of coronary artery after routine PTCA.

[Isolation, detection toxicity and structure of toxin from Beauveria bassiana]

In this experiment, the crude toxin from the metabolite of Beauveria bassiana was isolated and its toxicity was detected. The result shows that indicates toxin has toxicity on larva of Aedesalbopictus obvious. Though it with low toxicity to larva of Heliothis zea when swallowed, but has high toxicity when injected into the blood. For bacteria it only inhibites G+. When it applied to cultured cells of Spodoptera frugiperda sf-21, the regression equation of toxicity is y = 2.03 + 2.39x. The half lethal concentration (LC50) is 0.01751%. 95% believable limit is 0.01517-0.0202%. There are three substances which have similar atomic group when analysed by HPLC and infrared spectrum.

Viscoelastic flow in the lower crust after the 1992 landers, california, earthquake

Space geodesy showed that broad-scale postseismic deformation occurred after the 1992 Landers earthquake. Three-dimensional modeling shows that afterslip can only explain one horizontal component of the postseismic deformation, whereas viscoelastic flow can explain the horizontal and near-vertical displacements. The viscosity of a weak, about 10-km-thick layer, in the lower crust beneath the rupture zone that controls the rebound is about 10(18) pascal seconds. The viscoelastic behavior of the lower crust may help to explain the extensional structures observed in the Basin and Range province and it may be used for the analysis of earthquake hazard.

[Effects of isorhapotigenin and resveratrol on function of peripheral blood polymorphonuclear leukocytes from rabbits]

In effects of isorhapotigenin and resveratrol on chemotaxis and release of beta-glucuronidase from rabbit peripheral blood polymorphonuclear leukocytes stimulated with formylmethionyl-leucyl-phenyl-phenylalanine (fMLPP) were studied. The optimal concentration of fMLPP for the induction of chemotaxis of polymorphonuclear leukocytes was approximately at 5 x 10(-10) mol.L-1. fMLPP, at the concentration range of 10(-10)-10(-6) mol.L-1, dose-dependently increased the release of beta-glucuronidase from polymorphonuclear leukocytes. Isorhapotigenin and resveratrol both inhibited the chemotaxis of polymorphonuclear leukocytes stimulated with fMLPP(5 x 10(-10) mol.L-1). Isorhapotigenin, at the concentration range of 10(-5)-10(-4) mol.L-1, dose-dependently inhibited the release of beta-glucuronidase from polymorphonuclear leukocytes stimulated with fMLPP(10(-8) mol.L-1). Resveratrol, at the concentrations of 1 x 10(-5) and 3 x 10(-5) mol.L-1, was shown to dose-dependently inhibit beta-glucuronidase release from polymorphonuclear leukocytes stimulated with fMLPP(10(-8) mol.L-1).

Adenovirus 5 E1A-mediated tumor suppression associated with E1A-mediated apoptosis in vivo

Disruption of apoptotic pathways is a major factor in the multistep process of tumorigenesis, whereas induction of apoptosis can be important for tumor suppression and cancer therapy. The adenovirus type 5 E1A gene provides a useful tool to study the function of tumor suppression and apoptosis. E1A has been shown to induce apoptosis in different systems in vitro. However, this activity has not been well characterized in vivo. Therefore, the effect of this activity and the link to the in vivo biological function are not clear. To answer these questions, we introduced E1A into murine melanoma cells and characterized the biological features both in vitro and in vivo. Expression of the E1A gene does not affect the proliferation rate of tumor cells in vitro, but inhibits tumor growth in vivo. The in vitro analysis indicated that the E1A-expressing tumor cells are sensitive to serum depletion-induced apoptosis. Importantly, E1A-mediated apoptosis was also identified in vivo, suggesting this activity contributed to the tumor suppressive function. The in vivo apoptotic pattern was unique: most of the apoptotic cells were around the periphery of the tumors, implicating the interaction of these cells with stress stimuli in vivo. In addition, E1A also rendered the tumor cells susceptible to the cytotoxicity of other anticancer agents, a feature useful for improving the efficacy of cancer therapy. The results provide a functional link between in vitro activity and in vivo effects.

Detection of gsp oncogene in growth hormone-secreting pituitary adenomas and the study of clinical characteristics of acromegalic patients with gsp-positive pituitary tumors

OBJECTIVE

To investigate the incidence and clinical characteristics of gsp oncogene positive growth hormone-secreting adenomas of Chinese acromegalic patients.

METHODS

Continuously 40 patients were studied. Serum hormone levels of pituitary and target glands were measured and growth hormone (GH)-TRH stimulating tests were done before transsphenoidal or transfrontal hypophysectomy. Deoxyribonucleic acid (DNA) was extracted from the frozen tumor tissue, and the DNA fragment encompassing codon 201 and 227 of the Gs alpha gene was amplified by polymerase chain reaction (PCR). Point mutations at codon 201 and 227 were detected using PCR direct sequencing method in order to get the incidence of gsp oncogene in GH secreting adenomas.

RESULTS

Of 40 tumors studied, 22 (55%) were gsp positive. The point mutation from CGT (Arg) to TGT (Cys) at codon 201 was detected in 21 pituitary tumors, but the point mutation from CAG (Gln) to CTG (Leu) at codon 227 of the Gs alpha gene was found in only 1 tumor. All of the point mutations are heterozygous. The number of gsp positive patients which have 30% or more decrease of serum GH concentration after glucose inhibition is less than that of gsp negative patients (P = 0.042). Compared to gsp negative patients, most of gsp positive patients showed paradoxical response to TRH stimulation (P = 0.002). There were more gsp positive patients with the tumor diameter less than 25 mm (P = 0.029) and with normal GH levels in OGTT after surgery (P = 0.007).

CONCLUSIONS

Gsp mutation is one of the major intrinsic defects in the pathogenesis of growth hormone-secreting pituitary tumors and the identification of gsp mutation can be a reference for classification and prognosis of GH tumors.

[A prospective study on accidental deaths among 0-14-year-old children in Jiangsu, 1994-1995]

By stratified cluster random sampling, a prospective study on the accidental deaths of 0-14 years old children during 1994-1995 wsa carried on in a population size of 2.29 millions in four citys and nine counties in Jiangsu province. Results showed that the average mortality of accidents was 53.0 per 10(5) among children aged 0 to 14 and accidental death was the leading cause of deaths taking up 37.6% among the deaths of the 0-14 years old. Accidental deaths ranked fourth, took up 15.3% in infancy deaths making up about 70% in their deaths, and ranked first in the age groups 1-4 and 5-14. The three leading causes of accidental deaths in the urban and rural area were drowning, accidental suffocation and motor vehicle injuries. Accidental suffocation was the number one cause of accidental death in infants, making up 85% of the total accidental deaths. Drowning was the leading cause of accidental deaths in 1-4 and 5-14-year-old children, making up 70% and 50% of accidental deaths respectively. Motor vehicle injuries took the lead among accidental deaths in the cities.

Multiple isoforms of DNA methyltransferase are encoded by the vertebrate cytosine DNA methyltransferase gene

This manuscript tests the hypothesis that multiple forms of cytosine-DNA methyltransferase (MeTase) are expressed in vertebrates in vivo. Vertebrate genomes are distinguished by tissue- and gene-specific DNA methylation patterns. Specific methylation patterns are believed to encode epigenetic information. In distinction from the remarkable diversity of DNA methylation patterns, only one functional DNA MeTase cDNA has been identified to date in different vertebrate organisms. Using reverse transcription-polymerase chain reaction and RNase protection analyses, we show that the methyltransferase domain of the rat DNA MeTase is alternatively spliced in vivo, generating different in-frame variants of DNA MeTase in specific tissues. This process is developmentally regulated and is induced in PC12 cells by a known inducer of neuronal differentiation, nerve growth factor. The data presented here point toward a new mechanism for generating diversity of DNA MeTases and possibly diverse DNA methylation patterns.

Lamina-specific cell adhesion on living slices of hippocampus

Laminar distribution of fiber systems is a characteristic feature of hippocampal organization. Ingrowing afferents, e.g. the fibers from the entorhinal cortex, terminate in specific layers, which implies the existence of laminar recognition cues. To identify cues that are involved in the laminar segregation of fiber systems in the hippocampus, we used an in vitro assay to study the adhesion of dissociated entorhinal cells on living hippocampal slices. Here we demonstrate that dissociated entorhinal cells adhere to living hippocampal slices with a lamina-specific distribution that reflects the innervation pattern of the entorhino-hippocampal projection. In contrast, laminae which are not invaded by entorhinal fibers are a poor substrate for cell adhesion. Lamina-specific cell adhesion does not require the neural cell adhesion molecule or the extracellular matrix glycoprotein reelin, as revealed in studies with mutants. However, the pattern of adhesive cues in the reeler mouse hippocampus mimics characteristic alterations of the entorhinal projection in this mutant, suggesting a role of layer-specific adhesive cues in the pathfinding of entorhinal fibers. Lamina-specific cell adhesion is independent of divalent cations, is abolished after cryofixation or paraformaldehyde fixation and is recognized across species. By using a novel membrane adhesion assay, we show that lamina-specific cell adhesion can be mimicked by membrane-coated fluorescent microspheres. Recognition of the adhesive properties of different hippocampal laminae by growing axons, as either a growth permissive or a non-permissive substrate, may provide a developmental mechanism underlying the segregation of lamina-specific fiber projections.

Involvement of Ras in Bruton's tyrosine kinase-mediated JNK activation

Defects in Bruton's tyrosine kinase (Btk) result in B cell immunodeficiencies in humans and mice. Recent studies showed that Btk is required for maximal activation of JNK, a family of stress-activated protein kinases, induced by several extracellular stimuli including interleukin (IL)-3. On the other hand, IL-3-induced JNK activation is dependent on Ras. In the present study we have investigated whether Ras is involved in Btk-mediated JNK activation in BaF3 mouse pro-B cells. Overexpression of wild-type Btk protein in these cells enhanced JNK activation upon IL-3 stimulation, whereas expression of kinase-dead Btk partially suppressed JNK activation. Induced expression of the dominant negative Ras(N17) in the cells overexpressing wild-type Btk suppressed JNK activation. Importantly, overexpression of Btk enhanced the level of the GTP-bound, active form of Ras in response to IL-3 stimulation. Btk overexpression also increased the Shc-Grb2 association induced by IL-3 stimulation. Expression of either N17Ras or V12Ras did not impose any effects on Btk kinase activity. These data collectively indicate that Ras plays a role of an intermediary signaling protein in Btk-mediated JNK activation induced by the IL-3 signaling pathway.

[Separation of alkaloids in tea by high-speed counter-current chromatography]

Alkaloids extracted from the green tea were separated by high-speed counter-current chromatography. A series of experiments have been performed to investigate effects of different solvent system. A system of CHCl3-CH3OH-NaH2PO4(23 mmol/L) = (4:3:2) was selected, in which the upper phase was used as the stationary phase, and the lower phase as mobile phase. When acidity of solvent system is pH 5.6, three chemical components are very efficiently isolated by one injection of 50 mg sample mixture. Analyzing the eluted fractions by TLC, we know that one is caffeine, and the other is theophylline. In comparing the separation results by high-speed counter-current chromatography with those by TLC, the advantages of this method is verified. It should find wide applications of this technology for the separation of crude mixture of plant components.

Production of rhEPO with a serum-free medium in the packed bed bioreactor

Recombinant CHO (C2) cells producing human erythropoietin (rhEPO) were cultured with DMEM:F12 media containing 5% FBS for 8-10 days in a packed bed bioreactor, then rhEPO was produced with a serum-free medium (SFM-p) which was prepared in our laboratory. The SFM-p medium can support the growth of C2 cells and the production of rhEPO, and furthermore, it easily separates rhEPO from the culture supernatant. The cell culture in a packed bed bioreactor system using SFM-p was maintained in a stable condition for 20-25 days. The expression level of rhEPO was 12-28.4 mg/L. The bioreactor productivity was 71.0 mg/L.d and increased by 12-14 fold over that of the roller bottle. The glucose consumption rate was 21 g/L.d. At the end of 30 days of perfusion circulation, a final cell density of over 3.0 x 10(7)/ml of culture volume was achieved. Since the cells were entrapped in the polyester disk, the culture supernatant contained only a few detachment cells. Variations in lactate and ammonia production in the reactor were observed, and results showed that the productions of lactate and ammonia by the bioreactor were 3.5 g/L and 5 mmol/L, respectively, and did not affect the expression of interest protein. This experiment demonstrates that SFM-p is suitable for the growth and rhEPO production of recombinant C2 in the packed bed bioreactor.

Selective uptake of low density lipoprotein-cholesteryl ester is enhanced by inducible apolipoprotein E expression in cultured mouse adrenocortical cells

Apolipoprotein (apo) E is expressed at high levels by steroidogenic cells of the adrenal gland, ovary, and testis. The cell surface location of apoE in adrenocortical cells suggests that apoE may facilitate the uptake of lipoprotein cholesterol by either the endocytic or the selective uptake pathways, or both. To examine these possibilities, the human apoE gene was expressed in murine Y1 adrenocortical cells under control of an inducible tetracycline-regulated promoter. The results show that induction of apoE yielded a 2-2.5-fold increase in the uptake of low density lipoprotein-cholesteryl ester (LDL-CE) but had little effect on high density lipoprotein-CE uptake. Analysis of lipoprotein uptake pathways showed that apoE increased LDL-CE uptake by both endocytic and selective uptake pathways. In terms of cholesterol delivery to the adrenal cell, the apoE-mediated enhancement of LDL-CE selective uptake was quantitatively more important. Furthermore, the predominant effect of apoE expression was on the low affinity component of LDL-CE selective uptake. LDL particles incubated with apoE-expressing cells contained 0.92 +/- 0.11 apoE molecules/apoB after gel filtration chromatography, indicating stable complex formation between apoE and LDL. ApoE expression by Y1 cells was necessary for enhanced LDL-CE selective uptake. This result may indicate an interaction between apoE-containing LDL and cell surface apoE. These data suggest that apoE produced locally by steroidogenic cells facilitates cholesterol acquisition by the LDL selective uptake pathway.

A small proline-rich protein, spr1: specific marker for squamous lung carcinoma

We have identified a small proline-rich protein, spr1, which is a sensitive and specific marker for distinguishing squamous cancer from the other cell types of lung carcinoma. A rabbit antiserum against a 15-amino-acid peptide of the C-terminus of spr1 was prepared. The specificity of this antiserum was demonstrated in normal squamous tissues by Western blotting and immunohistochemical analysis. Expression of spr1 in 63 cases of formalin-fixed and paraffin-embedded human bronchogenic carcinoma was studied by immunohistochemical staining. For these 63 cases of bronchogenic carcinoma previously diagnosed by hematoxylin/eosin (H/E) staining, the number of spr1-positive cases/total number of H/E cases of each cell type of lung cancer were as follows: 20/20 of squamous carcinoma, 2/18 of adenocarcinoma, 4/14 of large-cell carcinoma, and 0/11 of small-cell lung carcinoma. Squamous differentiation evidenced by spr1 expression was substantiated by the presence of squamous features observed under transmission electron microscopy (TEM). We conclude that spr1 is a sensitive and specific marker for squamous bronchogenic carcinoma.

Rieger syndrome

PURPOSE

To discuss the clinic features of Rieger syndrome, the reasons of making wrong diagnosis, the way of treatment, and the research progress of its molecular characterization and gene mapping of this syndrome.

METHODS

Two cases of Rieger syndrome which affected a patient and his daughter were studied. Multiple clinical examinations including photography of anterior segment, gonioscopy and fundus, Humphrey perimetry, A-scan ultrasonography, multiple tonometry in a day and chromosome examination were performed. Most importantly, ultrasonic biomicroscope (UBM) was first used to show the abnormalities of anterior segment in this syndrome.

RESULTS

Gonioscopic examination revealed many mesoderm tissues remained and some parts of the iris adhered to cornea. In addition to cornea, iris and chamber angle, UBM showed that there was also hypoplasia of ciliary body. The result of the chromosome examination indicated normal.

CONCLUSIONS

Rieger syndrome is an autosomal-dominated disorder with mesoderm dysgenesis. Recent researches have confirmed that a locus for this syndrome maps to 4q25. Besides hypoplasia of cornea, iris and chamber angle, its ocular phenotype maybe include dysgenesis of ciliary body which is probably one of the reasons of secondary glaucoma.

Inhibition of nuclear factor-kappaB activity is involved in E1A-mediated sensitization of radiation-induced apoptosis

The adenoviral E1A protein has been implicated in the potentiation of apoptosis induced by various external stimuli, but the exact mechanism of that potentiation is not clear. In this study, we compared the sensitivity to ionizing gamma-irradiation of E1A transfectants with that of parental cells in a human ovarian cancer cell line (SKOV3.ip1); we found that the E1A transfectants became sensitive to radiation-induced apoptosis. Recently, activation of the transcription factor nuclear factor-kappaB (NF-kappaB) has been shown to play a key role in the anti-apoptotic pathway of radiation-induced apoptosis. In an attempt to determine whether NF-kappaB was involved in the E1A-mediated sensitization of radiation-induced apoptosis, we found that radiation-induced activation of NF-kappaB occurred in the parental cells but was blocked in the E1A transfectants. Furthermore, parental cells cotransfected with NF-kappaB and E1A were better protected from undergoing apoptosis upon irradiation than those transfected with E1A alone. Thus, our results suggest that inhibition of NF-kappaB activation by E1A is a plausible mechanism for E1A-mediated sensitization of radiation-induced apoptosis.

Adenovirus-mediated overexpression of the transcription factor E2F-1 induces apoptosis in human breast and ovarian carcinoma cell lines and does not require p53

Apoptosis is a mode of cell death that is carefully regulated based on cellular and environmental signals. The ability to modulate the individual cellular machinery and thereby to promote apoptosis is an important strategy in cancer therapy. It has previously been shown that overexpression of the transcription factor E2F-1 can induce apoptosis in quiescent rat embryo fibroblasts. This effect has been reported to occur in a p53-dependent manner. To investigate whether overexpression of E2F-1 could also induce apoptosis in human cancer cells, a recombinant adenovirus vector containing the transgene E2F-1 under control of the cytomegalovirus promoter (Ad5CMVE2F) was used to induce high levels of the E2F-1 protein in human breast and ovarian carcinoma cell lines. Significant morphological changes occurred in four of the five cell lines within 48 h of transduction with the Ad5CMVE2F. These changes were consistent with apoptosis, which was confirmed further by DNA fragmentation assay and fluorescence-activated cell sorting analysis. On the basis of these assays, which show that apoptosis occurred in those cell lines with mutations in the p53 gene, we suggest that the induction of E2F-1-mediated apoptosis does not require wild-type p53 when E2F-1 is overexpressed using an adenovirus-based strategy.

Some changes of receptor and postreceptor signal transduction regulated by somatostatin in pituitary hGH-secreting adenomas

OBJECTIVE

To investigate the disturbance in the function of SRIF receptor, Gi protein and Ca2+ channel in hGH adenoma cells and to evaluate their significance in the pathogenesis of pituitary hGH adenomas.

METHODS

All 25 patients with pituitary hGH adenoma who were involved in this study had typical acromegalic manifestation and high fasting serum hGH levels of > 5.0 micrograms/L which were not suppressed to < 3.0 micrograms/L by oral glucose tolerance test. The pituitary hGH adenoma tissue obtained from transphenoidal operation was digested by collagenase and the dispersed adenoma cells were cultured in the monolayer. The effects of octreotide (SMS), a long-acting agonist of somatostatin, on hGH secretion and intracellular cAMP level were observed and the influences of pertussis toxin (PT), an inhibitor of Gi protein, and Ca2+ ionophore A23187 or KCl on the inhibitory action of octreotide on hGH secretion were also investigated in the cultured pituitary hGH adenoma cells.

RESULTS

A total of 16.0% (4/25) of cultured pituitary hGH adenomas did not respond to octreotide (100 nmol). The inhibitory effect of octreotide on hGH secretion was not blocked by PT (50 ng/ml) and A23187 (10 mumol) or KCl (22.5 nmol) in 31.6% (6/19) and 35% (7/20) of hGH adenomas, respectively. The effects of octreotide on hGH secretion and intracellular cAMP levels were studied in 10 cultured hGH adenomas. Octreotide suppressed both hGH secretion and cAMP levels in 5 cases; inhibited only hGH secretion or the cAMP level in 3 cases and 1 case respectively; and affected neither hGH secretion nor cAMP level in the last case.

CONCLUSION

There were abnormalities in the SRIF receptor and/or postreceptor signal transduction in 16.0% of hGH adenomas which did not respond to octreotide. The defects in Gi and/or Ca2+ channels were found in 52.4% (11/21) of hGH adenomas which had responded to octreotide. These defects might induce diminution of the inhibitory action of SRIF on hGH secretion and might be the causes of hypersecretion in some pituitary hGH adenomas.

Characterization of immobilization of an enzyme in a modified Y zeolite matrix and its application to an amperometric glucose biosensor

A new approach to construct an amperometric biosensor is described. Without using bovine serum albumin-glutaraldehyde, glucose oxidase (GOx) was immobilized on a dealuminized Y zeolite (DAY)-modified platinum electrode to construct a glucose sensor. The large specific surface area of the zeolite substrate resulted in high enzyme loading. The immobilized GOx in this manner was stable and could maintain its high activity for at least 3 months. The interactions between the zeolite and the enzyme were investigated by means of Fourier transform infrared spectra, and the pore distribution and the surface acid property of DAY were preliminarily studied. The results showed that the hydrophilic property and the existing mesopores of DAY played important roles in the enzyme immobilization. This resulting biosensor exhibited good reproducibility and selectivity, owing to the uniform pore structure and unique ion-exchange property of the zeolite. The biosensor responded rapidly to glucose in the linear range from 2.0 x 10(-6) to 3.0 x 10(-3) M, with a detection limit of 0.5 microM.

Interactions between protein kinase C and pleckstrin homology domains. Inhibition by phosphatidylinositol 4,5-bisphosphate and phorbol 12-myristate 13-acetate

Pleckstrin homology (PH) domains comprised of loosely conserved sequences of approximately 100 amino acid residues are a functional protein motif found in many signal-transducing and cytoskeletal proteins. We recently demonstrated that the PH domains of Tec family protein-tyrosine kinases Btk and Emt (equal to Itk and Tsk) interact with protein kinase C (PKC) and that PKC down-regulates Btk by phosphorylation. In this study we have characterized the PKC-BtkPH domain interaction in detail. Using pure PKC preparations, it was shown that the Btk PH domain interacts with PKC with high affinity (KD = 39 nM). Unlike other tested phospholipids, phosphatidylinositol 4,5-bisphosphate, which binds to several PH domains, competed with PKC for binding to the PH domain apparently because their binding sites on the amino-terminal portion of the PH domains overlap. The minimal PKC-binding sequence within the Btk PH domain was found to correspond roughly to the second and third beta-sheets of the PH domains of known tertiary structures. On the other hand, the C1 regulatory region of PKCepsilon containing the pseudosubstrate and zinc finger-like sequences was found to be sufficient for strong binding to the Btk PH domain. Phorbol 12-myristate 13-acetate (PMA), a potent activator of PKC that interacts with the C1 region of PKC, inhibited the PKC-PH domain interaction, whereas the bioinactive PMA (4-alpha-PMA) was ineffective. The zeta isoform of PKC, which has a single zinc finger-like motif instead of the two tandem zinc finger-like sequences present in conventional and novel PKC isoforms, does not bind PMA. Thus, as expected, PH domain binding with PKCzeta was not interfered with by PMA. Further, inhibitors that are known to attack the catalytic domains of serine/threonine kinases did not affect this PKC-PH domain interaction. In contrast, the presence of physiological concentrations of Ca2+ induced less than a 2-fold increase in PKC-PH domain binding. These results indicate that PKC binding to PH domains involve the beta2-beta3 region of the Btk PH domain and the C1 region of PKC, and agents that interact with either of these regions (i.e. phosphatidylinositol 4,5-bisphosphate binding to the PH domain and PMA binding to the C1 region of PKC) might act to regulate PKC-PH domain binding.

Immunoreactive growth hormone in human peripheral T lymphocytes: encoding sequence of cDNA identical to that of the pituitary human growth hormone

OBJECTIVE

To detect the cDNA sequence of immunoreactive growth hormone (irGH) in human lymphocytes and to compare it with that of human growth hormone (hGH) in the pituitary.

METHODS

The mRNA of irGH in human peripheral blood mononuclear cells (PBMC) was detected by Northern blot analysis. The cDNA of irGH was obtained by reverse-transcriptase and polymerase chain reaction amplification and obtained by screening from a cDNA library of human T lymphocytes. The sequence of irGH cDNA was determined and compared with that of the pituitary hGH.

RESULTS

Very low level of irGH mRNA was detected in human PBMCs by Northern blot analysis. The cDNA sequence of the entire open reading frame of human irGH was 651 bp, which is identical to that of pituitary hGH.

CONCLUSIONS

The same hGH molecule can be produced by human pituitary somatotrophic cells and human peripheral lymphocytes.

Construction and overexpression of a synthetic gene for human DNA methylguanine methyltransferase: renaturation and rapid purification of the protein

A synthetic gene was constructed that encodes human DNA methylguanine methyltransferase (hMGMT). The synthetic gene was designed with a number of unique restriction sites to facilitate cassette mutagenesis and to reflect the preferences found among genes in Escherichia coli. Both the full-length gene and a gene for a functional variant (hMGMT delta C) that lacks the C-terminal 28 codons were constructed, and the genes were overexpressed using a T7 RNA polymerase promoter. The proteins are made in the form of insoluble aggregates but the truncated form of the protein (hMGMT delta C) has been successfully denatured, renatured, and purified to near homogeneity by ion exchange. Methyltransferase activity assays of hMGMT delta C demonstrate that the reconstituted protein has substantial DNA repair activity, though somewhat less than full-length hMGMT that had been expressed and purified in a soluble form. Mass spectrometry of a mixture of proteolytic fragments confirmed the protein sequence and indicated no detectable oxidation of the active site cysteine. The protein was determined to be monomeric by gel filtration chromatography, and circular dichroism spectra for renatured hMGMT delta C and fully soluble hMGMT are consistent with the renatured protein preparation being fully folded. Refolded hMGMT delta C had a curious propensity to form large aggregates in a time-dependent manner when injected into a dynamic light scattering instrument; this aggregation behavior was not observed for hMGMT purified in a soluble form. Differences in susceptibility to aggregation may account for differences in methyltransfer activity. Yields of purified protein were approximately 5 mg/liter of culture.

Immobilization of glucose oxidase with the blend of regenerated silk fibroin and poly(vinyl alcohol) and its application to a 1,1'-dimethylferrocene-mediating glucose sensor

The structure and properties of the blend of regenerated silk fibroin (RSF) and poly(vinyl alcohol) (PVA) were investigated. The two polymers in the blend are in the state of phase segregation. Infrared (IR) spectra indicate that the RSF in the blend maintains its intrinsic properties, thus, ethanol treatment can transfer silk I structure of RSF to silk II structure. The water absorption property and mechanical property of the blend are improved in comparison with those of RSF. The blend maintains the major merit of RSF, that is, it can immobilize glucose oxidase on the basis of the conformational transition from silk I structure to silk II structure. The properties of the immobilized enzyme are examined. Moreover, the second generation of glucose sensor based on the immobilized enzyme is fabricated and it has a variety of advantages including easy maintenance of enzyme, simplicity of construction, fast response time and high stability.

Investigation of plasma membrane-associated apolipoprotein E in primary macrophages

Our previous studies identified the lysosome as the compartment for degradation of newly synthesized apoE in primary macrophages. Lysosomal degradation of newly synthesized apoE is extensive and rapid (> 50% in 60 min). In the present study we tested the hypothesis that the macrophage cell surface is part of the itinerary of apoE in its path to the lysosomes. We therefore examined the existence and size of the apoE pool associated with the macrophage cell surface. Such a pool may not only provide a mechanism of targeting apoE for lysosomal degradation, by endocytosis, but also have important implications for the metabolism of lipoproteins by macrophages. Treatment of macrophages with heparin (10 micrograms/ml and 5 mg/ml) and heparinase I (1 U/ml), which releases substantial amounts of apoE from HepG2 cells, results in no additional release of apoE from macrophages. Treatment of macrophages with xyloside (1 mM) or GRGDTP (500 micrograms/ml) does not decrease the extent of cell-associated apoE. Both immunogold labeling, followed by electron microscopy, and immunofluorescent labeling and light microscopy further confirm the lack of significant amounts of cell surface-associated apoE in macrophages. In contrast, immunolabeled apoE is readily observed in permeabilized cells. Taken together, these data indicate the absence of significant apoE-glycosaminoglycan interaction at the macrophage cell surface. The lack of such an interaction is likely due to paucity of heparan sulfate proteoglycans on the macrophage cell surface, when compared to hepatocytes. Along with our previous observations. (Deng. J., V. Rudick, and L. Dory, 1995. J. Lipid Res. 36:2129-2140), these results suggest direct targeting of a portion of newly synthesized apoE from trans-Golgi network to lysosomes for degradation, without involving the plasma membrane and endocytosis.

Amphotericin B enzyme-linked immunoassay for clinical use: comparison with bioassay and HPLC

OBJECTIVE

To evaluate a new enzyme-linked immunosorbent assay (ELISA) for amphotericin B in serum samples. Results are compared with those obtained by HPLC and bioassay.

DESIGN

Comparison of results obtained by ELISA, HPLC, and bioassay.

METHODS

We developed a new ELISA using a polyclonal rabbit antibody to measure serum amphotericin B concentrations. Blinded samples of amphotericin B in concentrations of 0.15-78 micrograms/mL were prepared in human serum and assayed simultaneously by the ELISA, HPLC, and bioassay. The results of each assay were derived from standard curves and evaluated by using the Table Curve 2D computer program. These data were compared by using correlation analysis with evaluation of Pearson's correlation coefficient by Student's t-test.

RESULTS

ELISA and bioassay compared favorably at amphotericin B concentrations of 0.3-20 micrograms/mL with a correlation coefficient of r = 0.993, while ELISA and HPLC compared with a correlation coefficient of r = 0.944. The average coefficient of variation over the range 0.3-20.0 micrograms/mL was 28% +/- 7% for HPLC, 26% +/- 9% for ELISA, and 13% +/- 4% for bioassay. Comparison of all three assays revealed the highest correlation with the ELISA assay (r = 0.998) for the range of concentrations (0.3-20 micrograms/mL) routinely achieved. Samples containing concentrations in excess of 20 micrograms/mL could be diluted. Desiccation for concentrations less than 0.3 microgram/mL was not tested.

CONCLUSION

The determination of serum amphotericin B concentrations by ELISA gave results similar to those obtained by a bioassay and HPLC technique. Although variability appears greater with ELISA, the ease of performing yjis assay expedites the evaluation of amphotericin B concentrations from lipid formulations without interference from coadministered antibacterials of azole antifungals.

The role of calcium ion in the pathogenesis of human pituitary GH-secreting adenomas

To study the role of Ca2+ in the pathogenesis of pituitary growth hormone secreting adenomas, the function of Ca2+ in 23 cases of human pituitary GH-secreting adenoma was investigated in monolayer cell culture. It was found that Ca2+ channel blockers nicardipin and nifedipin inhibited basal and growth hormone releasing hormone (GRH)-stimulated GH secretion in 87.5% and 100.0% of the GH adenomas, respectively, demonstrating that in most human pituitary GH adenomas, the basal and GRH regulated GH secretion is Ca2+ dependent. The GRH and sometostatin (SRIF) agonist octreotide regulated the processes of GH secretion via Ca2+ had defects in different steps including receptor, postreceptor Ca2+ channel and Ca(2+)-GH secreting coupling in 6(66.6%) and 5(55.5%) cases of 9 GH adenomas respectively. Among them, the defects in GRH receptor and SRIF regulated Ca2+ channel are the main causes of the dysfunction of GH adenomas. These defects may be related to GH hypersecretion in GH adenomas. Our data provides advance evidences for intrinsic defects of GH adenomas.

Three-dimensional magnetic resonance imaging of the postmortem fetal heart

Five postmortem fetuses were scanned by magnetic resonance (MR) imaging. Of eight three-dimensional (3D) data sets reconstructed on an MGI workstation, five sets demonstrated detailed 3D fetal cardiac structures, and one depicted clear information regarding the disposition and compression of the heart and lungs in diaphragmatic hernia. This study has shown the potential of 3D MR imaging in support of postmortem examination and for interactive visual teaching of the fetal cardiac structures. The new technique may eventually be of significance in prenatal detection of cardiac abnormalities with the development of fast real-time MR imaging.

Hydrogen peroxide sensor based on coimmobilized methylene green and horseradish peroxidase in the same montmorillonite-modified bovine serum albumin-glutaraldehyde matrix on a glassy carbon electrode surface

A new approach to construct a second-generation amperometric biosensor is described. The classical dye methylene green as a probing-needle mediator and horseradish peroxidase as a base enzyme were coimmobilized in the same montmorillonite-modified bovine serum albumin (BSA)-glutaraldehyde matrix to construct a H2O2 sensor. The immobilization matrix was formed from the pretreated sodium montmorillonite colloid in which the enzyme and the cross-linker were dissolved. Immobilization of methylene green from the dye mother solution was attributed to the adsorption function of the montmorillonite, whereas immobilization of horseradish peroxidase was attributed to the cross-linking function of the BSA-glutaraldehyde as usual. Cyclic voltammetry and potentiostatic measurements indicated that methylene green efficiently mediated electrons from the base electrode to the enzyme in the matrix. The sensor responded rapidly to low H2O2 concentration and achieved 95% of the steady-state current in less than 20 s, with a detection limit of 4.0 x 10(-7) M H2O2.

[Detecting immunoreactive GH mRNA in human peripheral blood lymphocytes]

The present study demonstrats that immunoreactive GH mRNA is expressed at low level in normal human peripheral blood lymphocytes by RT-PCR amplification and hybridization. Northern blot analysis of total RNA from lymphocytes with a pituitary hGH cDNA probe revealed a faint transcript migrating almost coincident with pituitary hGH menssenger RNA. Reverse transcription-polymerase chain reaction from total RNA of lymphocytes by using hGH specific primers generated a predicted 702 base pair band with almost the same size as pituitary and also hybridized with pituitary hGH cDNA probe specifically in Southern blot analysis, which indicates a low level expression of GH-like mRNA in human peripheral blood lymphocytes.

The role of GRH mediated AC-cAMP system in the pathogenesis of human pituitary GH-secreting adenomas

OBJECTIVE

To investigate the role of AC-cAMP system in the transmission of the action of the growth hormone releasing hormone (GRH) on growth hormone (GH) release in pituitary GH-secreting adenomas.

METHODS

The effects of GRH (10(-7) mol/L) on intracellular cAMP levels and GH release and the effects of AC-cAMP stimulators, cholera toxin (Ct, 50 micrograms/L), forskolin (10(-5) ml/L) and db-cAMP (10(-3) mol/L) on GH secretion were studied in cultured cells of 21 GH-secreting adenomas obtained from operation for acromegalic patients.

RESULTS

GRH and Ct failed to stimulate GH secretion in 61.9% (13/21 cases) and 57.1% (12/21 cases) pituitary GH adenoma cell cultures respectively. Forskolin stimulated GH release in 88.9% (8/9 cases), while db-cAMP induced GH secretion in all cases tested (5/5 cases). The intracellular cAMP levels were elevated by GRH in the 4 out of 9 cases of tumor cell cultures, but not in the other 5 cases. According to the GH secretory responses to GRH and Ct, the 21 GH tumors were divided into 4 groups. In group A and B, GRH can stimulate GH release, but Ct has stimulative role only in group A. In group C and D, GRH fails to stimulate GH secretion. However group A can respond to Ct, but group D has no response.

CONCLUSIONS

The GH hypersecretion in most acromegalic patients is mainly due to the defects of pituitary adenoma cells, especially the abnormalities of GRH receptor and/or stimulative guanosine protein.

An amperometric new methylene blue N-mediating sensor for hydrogen peroxide based on regenerated silk fibroin as an immobilization matrix for peroxidase

A simple and effective procedure was described for the immobilization of peroxidase in regenerated silk fibroin membrane prepared from waste silk. The membranes of regenerated silk fibroin with or without peroxidase, before or after the ethanol treatment, were characterized by ir spectra. An amperometric H202 sensor, based on the immobilized peroxidase in regenerated silk fibroin membrane, in the use of new methylene blue N as an electron transfer mediator, was fabricated. The characteristics of the sensor with respect to linearity, response time, effect of pH and temperature, stability, and reproducibility were investigated. Dependences of Michaelis-Menten constant KMapp on the concentration of the mediator, and the applied potential were also studied and the results were presented. The sensor was highly sensitive to H2O2 with a detection limit of 1.0 x 10(-7)M and with response time of less than 40 s.

Entrapment of both glucose oxidase and peroxidase in regenerated silk fibroin membrane

Two enzmyes, glucose oxidase and peroxidase, were for the first time simultaneously immobilized in regenerated silk fibroin membrane. The structure and morphology of the regenerated silk fibroin membrane containing both glucose oxidase and peroxidase were investigated with IR spectra and SEM. The bienzymes do not change the structures of the regenerated silk fibroin in the membrane, which has an islands-sea structure. For the first time, an amperometric methylene green mediating sensor for glucose based on co-immobilization of both glucose oxidase and peroxidase in regenerated silk fibroin was constructed. Cyclic voltammetry and amperometry were used to test the suitability of methylene green shuttling electrons between peroxidase and the glassy carbon electrode. The bienzyme-based system offers fast response and high sensitivity of the sensor to glucose. The effects of pH, temperature, and the concentration of the mediator on the response current were evaluated, and the dependence of the Michaelis-Menten constant K(m)(app) on the concentration of the mediator was investigated.

Amphotericin B enzyme-linked immunosorbent assay

Our purpose was to develop and characterize an enzyme-linked immunosorbent assay (ELISA) which could measure the concentration of amphotericin B in serum. Amphotericin B was assayed by competition ELISA. Multiwell ELISA plates coated with amphotericin B (1.0 micrograms/ml) conjugated to bovine serum albumin were used to test replicates of serum samples spiked with amphotericin B. Purified rabbit polyclonal antibody against amphotericin B (1.4 micrograms/ml) was added subsequent to the instillation of samples spiked with unknown amounts of amphotericin B. Experiments were performed to test the sensitivity, specificity, precision, and accuracy of the assay. The ability to measure lipid-associated amphotericin B was also evaluated in preliminary studies. Analysis of reference samples containing amphotericin B yielded a traditional sigmoidal curve. The limits of detection were 0.15 to 156 micrograms/ml. The sensitivity of the assay was affected by light and temperature exposure. Assay specificity was altered only by the presence of nystatin, a polyene antifungal agent similar to amphotericin B. Intrarun (coefficient of variation = 3.0%) and interrun (coefficient of variation = 12.8%) coefficients of variation were calculated and were comparable to those in similar assays. The assay's correlation coefficient (r = 0.907) demonstrated a statistically significant correlation between the optical density of the sample and the concentration of drug in the sample. The amphotericin B ELISA's ease, precision, and overall accuracy suggest that this assay could be used for assessments of serum amphotericin B concentrations. Multiple research questions concerning the role of serum amphotericin B concentrations in toxicity and efficacy have gone unanswered because of the labor-intensive nature of the assays which have been available to date. The ability to easily and rapidly measure 40 duplicate samples containing amphotericin B should also prove to be a distinct advantage for clinical research or reference laboratories in addressing these questions.

[The role of Ca2+ in the pathogenesis of human pituitary GH-secreting adenomas]

Effects of Ca2+ channel blockers (nicardipin and nifedipin) and Ca2+ ionophore A23187 on the basal secretion and on the secretion stimulated by GRH or inhibited by SMS, a SRIF analogne of GH were investigated in monolayer cell cultures of 23 cases of human pituitary GH-secreting adenomas. The roles of GRH and SMS in 45Ca influx were investigated also. The GH secretion of most GH adenomas was depended on Ca2+, but the abnormality in different link of GH secretion mediated by Ca2+ was observed. The defects of receptor and post-receptor including Ca2+ channel and Ca(2+)-GH secretion couple regulated by GRH and SRIF were found in 66.7% and 55.6% of GH adenomas respectively. These abnormalities may contribute to GH hypersecretion in GH adenomas.

Fetal echocardiography in three and four dimensions

A three-dimensional (3D) acquisition system using an electromagnetic position sensor attached to a standard transducer on an unmodified ultrasound scanner was developed to capture two-dimensional (2D)-fetal echocardiograms at various positions and orientations. Operating in real-time directed M-mode allowed recording of 2D structural images and cardiac motion curves, from which the fetal cardiac phase could be determined. By digitising over 100 image frames for each scanning sequence, and by selecting frames at particular phases, 3D views of the fetal heart were reconstructed for each phase. Of 20 sequences of six fetuses scanned, 13 sequences successfully demonstrated usable 3D fetal heart structures, including four cardiac chambers, ventricular and atrial septa, foramen ovale and some of the cardiac valves and great vessels. Rearrangement of those phased 3D images into a cyclic sequence could generate dynamic 3D views of a beating fetal heart. We believe that, with further technical development, this new approach will be of use in the diagnosis of prenatal cardiac malformations and malfunctions, in in utero cardiac surgery and in fetal cardiology teaching.

Topology of prostaglandin H synthase-1 in the endoplasmic reticulum membrane

Prostaglandin H synthase-1 is an integral endoplasmic reticulum membrane protein which catalyzes a key control step in prostaglandin biosynthesis. The overall arrangement of the prostaglandin H synthase-1 polypeptide with respect to the endoplasmic reticulum membrane was examined in transiently transfected COS-1 cells, using immunofluorescence microscopy. A bacterial toxin, streptolysin-O, was used for selective plasma membrane permeabilization and a detergent, saponin, for general membrane permeabilization. Treated cells were probed with six antibodies specific for particular prostaglandin H synthase-1 peptide segments and one antibody specific for an inserted viral reporter epitope. Control experiments established that actin, a cytoplasmic marker, was accessible to fluorescein-labeled phalloidin after streptolysin-O treatment, whereas antibodies against protein disulfide isomerase, an endoplasmic reticulum lumenal marker, bound only after saponin treatment, Using this approach to investigate prostaglandin H synthase-1, it was found that streptolysin-O treatment was sufficient to obtain staining of intracellular membranes by antibodies specific for the endogenous C-terminal segment, for the viral reporter inserted at the C-terminus, and for the protease-sensitive region near arg277. In contrast, saponin treatment was necessary for staining by antibodies specific for peptides spanning residues 51-66, 156-170, and 377-390. Antibodies targeted against residues 483-496 did not stain transfected cells even after saponin permeabilization, although they did bind to detergent-solubilized prostaglandin H synthase-1. These results indicate that the C-terminus and arg277 regions of the synthase can be exposed on the cytoplasmic side of the endoplasmic reticulum membrane, whereas regions near N-glycosylation sites are confined to the endoplasmic reticulum lumen and residues 483-496 are inaccessible from either side of the endoplasmic reticulum membrane.

Lysosomal degradation and sorting of apolipoprotein E in macrophages

We previously reported that a substantial amount of newly synthesized apoE in mouse macrophages is degraded prior to secretion; a portion of this pool of apoE can be rescued by the addition of HDL3 to the incubation medium. In the present studies, the location and nature of the intracellular degradation of apoE were more closely examined. Inhibitors of protein trafficking (brefeldin A) as well as a number of protease inhibitors were used. The experiments using brefeldin A (5 micrograms/ml) clearly established that neither the endoplasmic reticulum nor the Golgi complex are the sites of apoE degradation. Using a pulse-chase design, [35S]apoE cannot be chased out in the presence of brefeldin A and remains undegraded within the cell. The accumulated apoE lacks the sialic acid residues, indicating that this final stage of processing must occur in the trans-Golgi network or later. Lysosomotropic agents, ammonium chloride and chloroquine, on the other hand, inhibit apoE degradation by over 70 and 80%, respectively, while total cell protein degradation remains unaffected. Similarly, a cocktail consisting of four lysosomal protease inhibitors (pepstatin, E-64, chymostatin, and antipain), inhibits specifically apoE degradation by over 60%. In contrast, ALLN, an inhibitor of Ca(2+)-dependent cysteine proteases, has a moderate effect on apoE degradation (30% inhibition) and a more pronounced effect on total protein degradation. These data suggest that the site of intracellular apoE degradation in the macrophage is the lysosome. These conclusions are supported by light and electron microscopy of macrophages, clearly showing the presence of immunoreactive apoE (along with cathepsin D) in the endosomal/lysosomal compartment of control and lysosomotropic agent-treated cells. In contrast, little or no labeling is seen in this compartment in brefeldin A-treated cells. At lower concentrations of the lysosomotropic agents, the extent of inhibition of apoE degradation is compensated for by its increased secretion, in a manner analogous to the effect of these agents on lysosomal enzymes. Higher concentrations of these agents, which lead to a profound inhibition of apoE degradation, also specifically block apoE secretion. The block in apoE secretion in the presence of high concentrations of chloroquine leads to undiminished or higher concentrations of immunoreactive apoE in the endosomal/lysosomal compartment, suggesting that apoE is targeted for lysosomal degradation directly, without prior secretion or surface association. These data strongly suggest pH-dependent sorting of apoE in macrophages to the degradative and secretory pathways and imply a protein-protein interaction in the process.

[Apoptosis of mouse MS-2 fibrosarcoma cells induced by photodynamic therapy with LDL-administered zinc-phthalocyanine]

Photodynamic destruction of MS-2 fibrosarcoma cells in mice induced by LDL-administered Zinc-phthalocyanine and red light irradiation was studied by electron microscopy. The pronounced structural changes such as chromatin condensation, disappearance of nuclear pores, karyopyknosis, karyorrhexis, leakage of chromatin aggregates, autophagocytosis, bleb formation on the cell surface, cytoplasmic vacuolization and cell fragmentation suggest that the tumor cell death was induced by apoptosis. However, its exact mechanism and regulating pathways remain to be further investigated.