Biomedical subjects

S A Harrison

Publications and source records attributed to S A Harrison.

At least 19 recordsLinked to original sources

PubMed2004

A pilot study of orlistat treatment in obese, non-alcoholic steatohepatitis patients.

BACKGROUND: Treatment options for non-alcoholic steatohepatitis (NASH) are limited. Weight loss remains the most recommended therapy. Orlistat is an effective adjunct to dietary weight loss therapy. AIM: To evaluate the efficacy of orlistat, given for 6 months to patients with obesity and biopsy confirmed NASH. METHODS: Ten obese patients with biopsy proven NASH were enrolled. Orlistat was given with meals for 6 months. Body Mass Index (BMI), liver enzymes, haemoglobin A1c, fasting lipids and glucose were assessed at baseline and at completion of the study. Paired liver histology was obtained. RESULTS: Six women and four men were enrolled. The mean weight loss was 22.7 lb and ranged from 0 to 24.3%. The following clinical values significantly improved: mean BMI: 43.4-39.8 (P = 0.007); mean haemoglobin A1c (%): 7.14-5.95 (P = 0.021); mean alanine aminotransferase (ALT) (U/L): 93 -54 (P = 0.009); and mean aspartate aminotransferase (AST) (U/L): 79-48 (P = 0.008). Steatosis improved in six patients, and fibrosis improved in three patients. CONCLUSIONS: Orlistat therapy and dietary counselling were associated with significant decreases in body weight, haemoglobin A1c, ALT and AST. A 10% or greater reduction in weight improved steatosis and fibrosis as well as haemoglobin A1c levels in the majority of patients treated for 6 months. Controlled trials of longer duration are warranted to assess for histopathologic improvement as well as cost-efficacy in comparison to diet and exercise alone.

Aged↗

PubMed2000

Clinical evaluation of a vaccinia-vectored Hantaan virus vaccine.

We evaluated a vaccinia-vectored vaccine for hemorrhagic fever with renal syndrome in clinical trials. A Phase I dose-escalation study in 16 volunteers divided into four groups demonstrated that subcutaneous inoculation of approximately 10(7) plaque-forming units of the recombinant virus was safe and immunogenic. Vaccination of a fifth group of 12 volunteers indicated that neutralizing antibody titers to both vaccinia virus and Hantaan virus were enhanced after a second inoculation. Comparing two routes of vaccination showed that scarification effectively induced neutralizing antibodies in vaccinia virus-naive volunteers but that subcutaneous inoculation was superior to scarification in vaccinia virus-immune individuals. A Phase II, double-blinded, placebo-controlled clinical trial was conducted among 142 volunteers. Two subcutaneous vaccinations were administered at 4-week intervals. Neutralizing antibodies to Hantaan virus or to vaccinia virus were detected in 72% or 98% of vaccinia virus-naive volunteers, respectively. In contrast, only 26% of the vaccinia virus-immune volunteers developed neutralizing antibody responses to Hantaan virus. J. Med. Virol. 60:77-85, 2000. Published 2000 Wiley-Liss, Inc.

Antibodies, Viral↗

PubMed2000

Telemedical evaluation and management of retinopathy of prematurity using a fiberoptic digital fundus camera.

OBJECTIVE: We sought to determine whether retinopathy of prematurity (ROP) can be evaluated and managed telemedically. DESIGN: Multicenter noncomparative case series. PARTICIPANTS: Ten patients (19 eyes) with ROP were evaluated and treated per standard of care and imaged with the RetCam 120 digital fundus camera (Massie Research Laboratories, Inc., Dublin, CA). INTERVENTION: Images were transmitted to a remote site for evaluation and management recommendations. MAIN OUTCOME MEASURES: Telemedical evaluations and management recommendations were compared with traditional on-site standard of care evaluations and treatments. RESULTS: The identification of Plus disease at the remote site was accurately identified in 95% of eyes. Prethreshold, threshold, and stage 4 or 5 ROP were correctly detected in 17 of 19 (89%) eyes. CONCLUSIONS: Results indicate ROP can be evaluated and treatment recommendations made at remote sites with telemedicine strategies.

Diagnostic Techniques, Ophthalmological↗

PubMed1997

Endogenous endophthalmitis caused by Streptococcus mitis.

PURPOSE: To report endogenous endophthalmitis caused by Streptococcus mitis. METHODS: A 3-year-old girl was hospitalized for possible retinoblastoma after she suddenly developed a red and sensitive left eye. After administration of anesthesia, we examined the patient and obtained samples of aqueous, vitreous, and blood for culture. RESULTS: Blood and vitreous cultures grew S mitis. Intravenous and intravitreal injections of antibiotics were used to treat the infection. CONCLUSIONS: Streptococcus mitis should be considered a cause of endogenous endophthalmitis.

Administration, Topical↗

PubMed1996

Interscalene anesthesia for shoulder arthroscopy in a community-sized military hospital.

The first 100 consecutive shoulder arthroscopic procedures performed under interscalene anesthesia at a small community-sized military hospital are the basis of this report. This method of anesthesia was compared with 100 shoulder arthroscopies performed in a previous 2-year time period under general anesthesia. A variety of arthroscopic and subsequent open reconstructive procedures about the shoulder were performed using both techniques. Using the interscalene method, 87 regional blocks were entirely successful. Thirteen patients required conversion to general anesthesia for adequate pain control; however, 4 of these had a complete block in the recovery room and required no postoperative narcotics. Seven patients required supplementation with local anesthetic when an open procedure became necessary. There were no major complications. Minor complications included 5 patients with transient Horner's syndrome, 4 patients who experienced anxiety, which was controlled with sedation, and 3 with nausea or pruritus. Interscalene anesthesia provided excellent intraoperative and postoperative analgesia with low morbidity. On a subsequent questionnaire, all patients with a successful block reported that they were extremely satisfied with their experience. Ten patients who had previous shoulder surgery under general anesthesia preferred the interscalene method. In summary, interscalene anesthesia proved to be an excellent method of anesthesia for shoulder arthroscopy. The technique is reproducible within the resources available in most community-level hospitals.

Adolescent↗

PubMed1996

Occupational therapy task observation scale (OTTOS): a rapid method for rating task group function of psychiatric patients.

OBJECTIVE: We designed a simple rating instrument, the Occupational Therapy Task Observation Scale (OTTOS), to facilitate evaluation and documentation of patient performance during occupational therapy task groups and to improve the communication between occupational therapists and other treatment team members. METHOD: After analysis of other rating instruments, a preliminary version of OTTOS was designed, extensively field tested, and further modified. Interrater reliability was determined, and validity was tested against three established rating instruments: the Bay Area Functional Performance Evaluation, the Comprehensive Occupational Therapy Evaluation Scale, and the Milwaukee Evaluation of Daily Living Skills. RESULTS: The final version of OTTOS contains two parts, 10 items for evaluation of specific task functions and 5 items for rating general behavior. Field use demonstrated that the scale successfully tracked changes in functional capacity and included most facets of patient function evaluated during task groups. Use of OTTOS required minimal training, and scoring required less than 2 min for each patient. The correlation between the scores of experienced occupational therapists was high (.92 for the total scores). The correlation between OTTOS and the other rating instruments ranged from .880 to .340; the highest correlations, as expected, were with test subscales that most closely resembled OTTOS: CONCLUSION: Preliminary data indicated that OTTOS offers a reliable and valid method for rapidly rating the function of patients with psychiatric illness attending task groups. In addition, use of OTTOS improved the communication between occupational therapists and other health care providers, facilitated the education of occupational therapy students, and met the documentation requirements of third-party payers.

Humans↗

PubMed1996

Case study: high acuity to long-term.

High acuity nursing involves caring for clients who have potentially life-threatening conditions. This care is described as required, due to a disruption in one or more principal organ systems. How high acuity care is differentiated from acute or long term care may be dependent on the client's initial overall condition and/or predicted outcome. The client discussed has sustained a spinal cord injury at the C5 level. This presentation will demonstrate how clients may continually pass through high acuity care circumstances, acute care, to ultimately a long term care situation. Description of this client in a case study format may result in a learning experience for practitioners concerned with the physiological and the psychosocial aspects of their clients who require high acuity, acute and/or long term care. Car or motorcycle accidents account for at least half of all spinal cord injuries. Most are injuries involving cervical segments number 5 and 6. Cord damage can ascend or descend as much as three levels above or below the injury, due to edema or cord compression post trauma (Woll, 1986). Accidents with severe damage to the spinal cord at the C5 level can result in quadriplegia. Injuries of this magnitude can be either complete or incomplete. Complete injuries cause a "... loss of all conscious motor and/or sensory function below the level of injury" while incomplete injury spares some function, motor and/or sensory (Zejdlik, 1992, p.66). The purpose of this article is to present a client case study as a model for practitioners who practice in high acuity, acute, and long term situations. Two nursing theories (self-care deficit and adaptation) will be used as a framework for the case study. An assessment of the client's physical findings, including history, physical examination, and psychosocial status will be described. Nursing diagnoses and nursing interventions for two specific clinical problems will be presented. Recommendations for future research, nursing care and/or referrals will be outlined.

Acute Disease↗

PubMed1995

Identification of noise sources in surface recording of spinal somatosensory evoked potentials.

The poor signal-to-noise ratio associated with the acquisition of evoked potentials is a well established fact. The problem is compounded if non-invasive techniques, using surface electrodes, are employed. The paper identifies several sources of noise associated with the acquisition of spinal somatosensory evoked potentials using surface electrodes. In addition, the relative contribution of these sources is determined experimentally for six spinal levels ranging from lower lumbar to upper thoracic. These data will prove useful in the design of digital signal processing schemes such as adaptive noise cancellation, where levels of uncorrelated noise severely limit system performance.

Electric Impedance↗

PubMed1992

Activation of cell surface glucose transporters measured by photoaffinity labeling of insulin-sensitive 3T3-L1 adipocytes.

Several studies have demonstrated that the intrinsic catalytic activity of cell surface glucose transporters is highly regulated in 3T3-L1 adipocytes expressing GLUT1 (erythrocyte/brain) and GLUT4 (adipocyte/skeletal muscle) glucose transporter isoforms. For example, inhibition of protein synthesis in these cells by anisomycin or cycloheximide leads to marked increases in hexose transport without a change in the levels of cell surface glucose transporter proteins (Clancy, B. M., Harrison, S. A., Buxton, J. M., and Czech, M. P. (1991) J. Biol. Chem. 266, 10122-10130). In the present work the exofacial hexose binding sites on GLUT1 and GLUT4 in anisomycin-treated 3T3-L1 adipocytes were labeled with the cell-impermeant photoaffinity reagent [2-3H]2-N-[4-(1-azitrifluoroethyl)benzoyl]-1,3-bis- (D-mannos-4-yloxy)-2-propylamine [( 2-3H] ATB-BMPA) to determine which isoform is activated by protein synthetic blockade. As expected, a 15-fold increase in 2-deoxyglucose uptake in response to insulin was associated with 1.7- and 2.6-fold elevations in plasma membrane GLUT1 and GLUT4 protein levels, respectively. Anisomycin treatment of cultured adipocytes for 5 h produced an 8-fold stimulation of hexose transport but no increase in the content of glucose transporters in the plasma membrane fraction as measured by protein immunoblot analysis. Cell surface GLUT1 levels were also shown to be unaffected on 3T3-L1 adipocytes in response to anisomycin using an independent method, the binding of an antiexofacial GLUT1 antibody to intact cells. In contrast, anisomycin fully mimicked the action of insulin to stimulate (about 4-fold) the radiolabeling of GLUT1 transporters specifically immunoprecipitated from intact 3T3-L1 adipocytes irradiated after incubation with [2-3H] ATB-BMPA. Photolabeling of GLUT4 under these conditions was also significantly enhanced (1.8-fold) by anisomycin treatment, but this effect was only 15% of that caused by insulin. These results suggest that: 1) the photoaffinity reagent [2-3H]ATB-BMPA labels those cell surface glucose transporters present in a catalytically active state rather than total cell surface transporters as assumed previously and 2) inhibition of protein synthesis in 3T3-L1 adipocytes stimulates sugar transport primarily by enhancing the intrinsic catalytic activity of cell surface GLUT1, and to a lesser extent, GLUT4 proteins.

3T3 Cells↗

PubMed1992

Complex regulation of simple sugar transport in insulin-responsive cells.

Facilitated sugar entry into mammalian cells is catalysed by multiple isoforms of the glucose transporter and regulated by hormonal stimuli, nutritional status and oncogenesis. A large reserve of latent glucose transport capacity must be maintained by muscle and adipose cells that are sensitive to insulin, the primary activator of sugar uptake after feeding. Intracellular sequestration of sugar transporters accounts for a large part of this latent capacity, but new findings suggest that there is also reversible suppression of intrinsic catalytic activity of those glucose transporters residing at the cell surface. The mechanism of this suppression appears to be occlusion or disruption of the exofacial sugar-binding sites on the glucose-transporter proteins.

3T3 Cells↗

PubMed1991

Evidence that functional erythrocyte-type glucose transporters are oligomers.

In this study we tested the hypothesis that functional erythrocyte-type glucose transporters (GLUT1) exist as oligomeric complexes by expressing chimeric transporter proteins in Chinese hamster ovary cells harboring endogenous GLUT1 transporters. The chimeric transporters were GLUT1-4c, in which the 29 C-terminal residues of human GLUT1 were replaced by the 30 C-terminal residues of rat skeletal muscle glucose transporter (GLUT4), and GLUT1n-4, containing the N-terminal 199 residues of GLUT1 and the 294 C-terminal residues of GLUT4. Endogenous GLUT1 was quantitatively co-immunoprecipitated by using an anti-GLUT4 C-terminal peptide antibody from detergent extracts of Chinese hamster ovary cells expressing either of the chimeric proteins, as detected by immunoblotting the precipitates with an anti-GLUT1 C-terminal peptide antiserum. No co-immunoprecipitation of native GLUT1 with native GLUT4 from extracts of 3T3-L1 adipocytes, which contain both these transporters, was observed with the same antibody. These data are consistent with the hypothesis that GLUT1 transporters exist as homodimers or higher order oligomers and that a major determinant of oligomerization is located within the first 199 residues of GLUT1.

3T3 Cells↗

PubMed1991

Evidence that erythroid-type glucose transporter intrinsic activity is modulated by cadmium treatment of mouse 3T3-L1 cells.

Previous studies suggest that regulation of hexose uptake in Chinese hamster ovary fibroblasts can occur by alterations in glucose transporter intrinsic activity without changes in cell surface transporter number (Harrison, S. A., Buxton, J. M., Helgerson, A. L., MacDonald, R. G., Chlapowski, F. J., Carruthers, A., and Czech, M. P. (1990) J. Biol. Chem. 265, 5793-5801). We tested this hypothesis using 3T3-L1 fibroblasts and adipocytes which exhibit 5-6-fold increases in 2-deoxyglucose or 3-O-methylglucose uptake when exposed to low micromolar concentrations of cadmium for 18 h. Cadmium treatment decreased the apparent Km of 3T3-L1 fibroblasts for 3-O-methylglucose influx from approximately 28 to 9 mM and increased the apparent Vmax by 2-3-fold. These fibroblasts lack the skeletal muscle/adipocyte-type (GLUT4) transporter and showed only a small increase in total cellular immunoreactive HepG2 type (GLUT1) transporter in response to cadmium. Furthermore, cell surface GLUT1 levels did not change in 3T3-L1 fibroblasts exposed to cadmium, as assessed by the binding to intact cells of an antibody which recognizes an extracellular GLUT1 epitope. Insulin enhanced 2-deoxyglucose uptake 2-fold in 3T3-L1 fibroblasts, but did not further stimulate cadmium-activated transport rates. In contrast, insulin stimulated hexose transport 15-fold in 3T3-L1 adipocytes, which express both GLUT1 and GLUT4 proteins, and this effect was fully additive with the 5-fold effect of cadmium. Cadmium had little or no effect on immunoreactive GLUT1 or GLUT4 in isolated 3T3-L1 adipocyte plasma membranes. In contrast, insulin action led to marked recruitment (3-fold) of GLUT4 to the plasma membrane fraction in adipocytes treated with or without cadmium. Taken together, these data are consistent with the hypothesis that cadmium-activated sugar uptake is catalyzed by GLUT1, whereas insulin-stimulated sugar uptake is catalyzed predominantly by GLUT4 in 3T3-L1 adipocytes. Furthermore, the data suggest that the GLUT1 transporter can undergo significant increases in intrinsic catalytic activity in response to cadmium treatment of 3T3-L1 fibroblasts and adipocytes.

3-O-Methylglucose↗

PubMed1991

Suppressed intrinsic catalytic activity of GLUT1 glucose transporters in insulin-sensitive 3T3-L1 adipocytes.

Previous studies indicated that the erythroidtype (GLUT1) glucose transporter isoform contributes to basal but not insulin-stimulated hexose transport in mouse 3T3-L1 adipocytes. In the present studies it was found that basal hexose uptake in 3T3-L1 adipocytes was about 50% lower than that in 3T3-L1 or CHO-K1 fibroblasts. Intrinsic catalytic activities of GLUT1 transporters in CHO-K1 and 3T3-L1 cells were compared by normalizing these hexose transport rates to GLUT1 content on the cell surface, as measured by two independent methods. Cell surface GLUT1 levels in 3T3-L1 fibroblasts and adipocytes were about 10- and 25-fold higher, respectively, than in CHO-K1 fibroblasts, as assessed with an anti-GLUT1 exofacial domain antiserum, delta. The large excess of cell surface GLUT1 transporters in 3T3-L1 adipocytes relative to CHO-K1 fibroblasts was confirmed by GLUT1 protein immunoblot analysis and by photoaffinity labelling (with 3-[125I]iodo-4-azidophenethylamido-7-O-succinyldeacetylforskoli n) of glucose transporters in isolated plasma membranes. Thus, GLUT1 intrinsic activity is markedly reduced in 3T3-L1 fibroblasts compared with the CHO-K1 fibroblasts, and further reduction occurs upon differentiation to adipocytes. Intrinsic catalytic activities specifically associated with heterologously expressed human GLUT1 protein in transfected CHO-K1 versus 3T3-L1 cells were determined by subtracting appropriate control cell values for hexose transport and delta-antibody binding from those determined in the transfected cells expressing high levels of human GLUT1. The results confirmed a greater than 90% inhibition of the intrinsic catalytic activity of human GLUT1 transporters on the surface of mouse 3T3-L1 adipocytes relative to CHO-K1 fibroblasts. We conclude that a mechanism that markedly suppresses basal hexose transport catalyzed by GLUT1 is a major contributor to the dramatic insulin sensitivity of glucose uptake in 3T3-L1 adipocytes.

3-O-Methylglucose↗

PubMed1991

Protein synthesis inhibitors activate glucose transport without increasing plasma membrane glucose transporters in 3T3-L1 adipocytes.

In this study, we tested the hypothesis that hexose transport regulation may involve proteins with relatively rapid turnover rates. 3T3-L1 adipocytes, which exhibit 10-fold increases in hexose transport rates within 30 min of the addition of 100 nM insulin, were utilized. Exposure of these cells to 300 microM anisomycin or 500 microM cycloheximide caused a maximal, 7-fold increase in 2-deoxyglucose transport rate after 4-8 h. The effects due to either insulin (0.5 h) or anisomycin (5 h) on the kinetics of zero-trans 3-O-methyl[14C]glucose transport were similar, resulting in 2.5-3-fold increases in apparent Vmax values (control Vmax = 1.6 +/- 0.3 x 10(-7) mmol/s/10(6) cells) coupled with approximately 2-fold decreases in apparent Km values (control Km = 23 +/- 3.3 mM). Insulin elicited the expected increases in plasma membrane levels of HepG2/erythrocyte (GLUT1) and muscle/adipocyte (GLUT4) transporters (1.6- and 2.8-fold, respectively) as determined by protein immunoblotting. In contrast, neither total cellular contents nor plasma membrane levels of these two transporter isoforms were increased when 3T3-L1 adipocytes were treated with either anisomycin or cycloheximide. 3-[125I]Iodo-4-azidophenethylamido-7-O-succinyldeacetylforskoli n labeling of glucose transporters in plasma membrane fractions of similarly treated cells was also unaffected by these agents. Thus, a striking discrepancy was observed between the marked increase in cellular hexose transport rates due to these protein synthesis inhibitors and the unaltered amounts of glucose transporter proteins in the plasma membrane fraction. These data indicate that short-term protein synthesis inhibition in 3T3-L1 adipocytes leads to large increases in the intrinsic catalytic activity of one or both of the GLUT1 and GLUT4 transporter isoforms.

3-O-Methylglucose↗

PubMed1990

Insulin regulation of hexose transport in mouse 3T3-L1 cells expressing the human HepG2 glucose transporter.

Complementary DNA encoding a HepG2 cell-facilitated glucose transporter (GLUT1) was subcloned into a metal-inducible, mammalian expression vector, pLEN. Mouse 3T3-L1 fibroblasts transfected with this new construct, pLENGT, exhibited zinc-inducible expression of human glucose transporter mRNA, protein, and glucose transport activity, before and after differentiation into adipocytes. Both mouse host GLUT1 and expressed human GLUT1 proteins distributed about equally between 3T3-L1 adipocyte plasma membranes and low density microsomal membranes, while host skeletal muscle/adipocyte-type glucose transporter (GLUT4) was concentrated in the latter fraction. Mouse GLUT1 and GLUT4 proteins and the constitutively expressed human GLUT1 protein in pLENGT adipocytes were all redistributed from low density microsomal membrane to plasma membrane fractions in response to insulin. Insulin stimulated 2-deoxyglucose uptake in untransfected fibroblasts about 2-fold, while untransfected adipocytes displayed a 14-fold increase in deoxyglucose uptake in response to insulin. Both the expression of human GLUT1 protein and basal 2-deoxyglucose uptake by 75 microM zinc-treated pLENGT fibroblasts and adipocytes were increased approximately 3-fold over untransfected cells. In such pLENGT fibroblasts expressing human GLUT1 protein, however, the absolute values for insulin-stimulated increases in sugar uptake were no different than in control fibroblasts. As was observed in pLENGT fibroblasts, the increased basal sugar uptake by pLENGT adipocytes was additive with the insulin-stimulated increase in the rate of sugar uptake and, therefore, the -fold stimulation by insulin was markedly reduced. These data indicate that: 1) the membrane distributions of a glucose transporter protein, which is not responsive to insulin in HepG2 cells, and both mouse GLUT1 and GLUT4 glucose transporter isoforms are regulated by insulin in mouse 3T3-L1 adipocytes, and 2) the expressed human GLUT1 appears to contribute significantly to the rate of basal uptake but not to the insulin-stimulated increase in 2-deoxyglucose uptake by 3T3-L1 fibroblasts and adipocytes.

Adipose Tissue↗

PubMed1990

Collagen shield delivery of amphotericin B.

By using a high-pressure liquid chromatography assay, we investigated the ability of collagen shield therapeutic contact lenses to release amphotericin B and deliver it to the anterior segment of rabbit eyes. In vitro studies showed that presoaked collagen shields released most of the amphotericin B within the first hour of elution. We compared the corneal and aqueous humor amphotericin B levels produced by collagen shields soaked in amphotericin B and frequent-drop therapy at four time points over a six-hour period. The collagen shields soaked in amphotericin B produced corneal levels that were higher than those produced by frequent-drop therapy at one hour, equivalent to drop therapy at two and three hours, and lower than drop therapy at six hours. There were no differences in amphotericin B levels in aqueous humor at any time point between rabbits treated with collagen shield delivery and rabbits treated with frequent-drop delivery. The results of this study suggest that amphotericin B delivery to the cornea by collagen shields is comparable to frequent-drop delivery but has the potential benefit of added convenience and compliance.

Administration, Topical↗

PubMed1990

Insulin action on activity and cell surface disposition of human HepG2 glucose transporters expressed in Chinese hamster ovary cells.

Complementary DNA encoding a facilitative glucose transporter was isolated from a human hepatoma cell line (HepG2) cDNA library and subcloned into a metal-inducible mammalian expression vector, pLEN (California Biotechnology) containing human metallothionein gene II promoter sequences. Chinese hamster ovary (CHO) cells transfected with this transporter expression vector, pLENGT, exhibited a 2-17-fold increase in immunoreactive HepG2-type glucose transporter protein, as measured by protein immunoblotting with antipeptide antibodies directed against the HepG2-type glucose transporter C-terminal domain. Expression of the human glucose transporter was verified by protein immunoblotting with a mouse polyclonal antiserum that recognizes the human but not the rodent HepG2-type transporter. 2-Deoxy-D-glucose uptake was increased 2-7-fold in transfected cell lines. Polyclonal antisera directed against purified red blood cell glucose transporter were raised in several rabbits. Antiserum from one rabbit, delta, was found to bind to the surface of intact red cells but not to inside-out red cell ghosts. Using this delta-antiserum in intact cell-binding assays, 1.6-9-fold increases in cell surface expression of the human glucose transporter were measured in CHO-K1 cell lines transfected with the transporter expression vector. Measurements of total cellular glucose transporter immunoreactive protein using anti-HepG2 transporter C-terminal peptide serum, cell surface glucose transporter protein using delta-antiserum and 2-deoxyglucose uptake revealed proportional relationships among these parameters in transfected cell lines expressing different levels of transporter protein. Insulin increased 2-deoxyglucose uptake 40% in control CHO-K1 cells and in CHO-K1 cells expressing modest levels of the human glucose transporter protein. However, stimulation of sugar-uptake by insulin was only 10% in cells overexpressing human glucose transporter protein 9-fold, and no effect of insulin on sugar uptake was detected in several cell lines expressing very high levels (12-17-fold over controls) of human HepG2 glucose transporter protein. No insulin stimulation of anti-cell surface glucose transporter antibody binding was detected in any control or transfected CHO-K1 cell lines. These data indicate that a glucose transporter protein that is insensitive to insulin in HepG2 cells is regulated by insulin when expressed at low but not at high levels in insulin-response CHO-K1 cells. Additionally, the results suggest that insulin does not increase 2-deoxyglucose uptake by increasing the number of cell surface HepG2-type glucose transporters in CHO-K1 fibroblasts.

Animals↗

PubMed1990

Modulation of HLA antigen expression on conjunctival fibroblasts by gamma-interferon.

We investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to induce class II HLA antigen expression on human conjunctival fibroblasts in cell culture. Cultures were established by explanting subconjunctival tissue from normal donor globes. Fibroblasts were treated with rhIFN-gamma at concentrations ranging from 1 to 500 units/ml and incubated for 1, 3 and 6 days. HLA antigens were detected by immunofluorescence using monoclonal antibodies in conjunction with flow cytometry. Class I antigen was identified using a monoclonal antibody directed against Beta-2 microglobulin (a component of the class I antigen complex). Class II histocompatibility antigens were detected using monoclonal antibodies specific for HLA-DR, HLA-DP and HLA-DQ. Class I antigen was present on all cells prior to induction and showed a trend toward increased density after treatment with rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, class II antigens were induced in a dose- and time-dependent fashion. HLA-DR expression was most sensitive to induction by rhIFN-gamma, followed by HLA-DP, and then HLA-DQ. The up-regulation of HLA class I antigen expression and the inducible expression of class II antigens following exposure to rhIFN-gamma suggest that conjunctival fibroblasts have the potential to participate in immunologic diseases of the external eye.

Adult↗