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Biomedical subjects

J A Kern

Publications and source records attributed to J A Kern.

106 records · Page 6Linked to original sources
PubMed1986

The role of the accessory cell in mitogen-stimulated human T cell gene expression.

The role of the accessory cell in optimizing T cell proliferative responses to mitogens is a well known but poorly understood phenomenon. To further dissect the function of the accessory cell in allowing T cell proliferation, we compared mitogen-induced c-myc, interleukin 2 (IL 2), and IL 2 receptor gene expression in peripheral blood mononuclear cells (PBMC) and in T cells rigorously depleted of accessory cells through differential adherence and anti-Dr (anti-class II major histocompatibility antigen) monoclonal antibody complement-directed cytotoxicity. In cultures stimulated with phytohemagglutinin (PHA), a mitogen that requires accessory cells to induce T cell proliferation, expression of all measured genes was accessory cell dependent, since accumulation of their mRNA in PBMC was greater than that in cultures depleted of accessory cells. These genes varied in their accessory cell dependence, with IL 2 expression most dependent, c-myc expression least dependent, and IL 2 receptor expression intermediate in dependency. Use of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or ionomycin, mitogens that stimulate T cell proliferation independent of accessory cells, induced equal levels of gene expression in PBMC and in T cells depleted of accessory cells. These results suggest that PHA-stimulated T cells are dependent on an accessory cell signal(s) for optimal expression of the genes for c-myc, IL 2, and IL 2 receptor, and for proliferation. In addition, this signal(s) appears to be delivered early in the course of T cell activation events, since it can be bypassed by mitogens that directly activate protein kinase C (TPA) or induce calcium translocation (ionomycin). In addition, these data provide further evidence that expression of the c-myc protooncogene is insufficient for T cell mitogenesis, since PHA-induced accumulation of c-myc mRNA was only partially accessory cell dependent, whereas proliferation was completely accessory-cell dependent.

Antigen-Presenting Cells↗
PubMed1986

IL 2 alone is mitogenic only for Tac-positive lymphocytes in human peripheral blood.

To investigate the ability of interleukin 2 (IL 2) alone to induce proliferation of resting human lymphocytes, we stimulated human peripheral blood mononuclear cells (PBMC) with an immunopurified preparation of IL 2 or with phytohemagglutinin (PHA). Proliferation and the percent of cells expressing IL 2 receptors were assessed over 6 days of culture. Regardless of the stimulus, the percent of cells bearing an IL 2 receptor paralleled the amount of proliferation, and proliferation was inhibited by an anti-IL 2 receptor monoclonal antibody (anti-Tac). When stimulated by IL 2 alone, less than 8% of PBMC expressed an IL 2 receptor after 24 hr of culture. Stimulation by IL 2 caused both proliferation and IL 2 receptor expression to increase over the entire culture period (routinely to 75,000 cpm and 50% respectively). When colchicine was added (to inhibit cell division), the percent of cells bearing an IL 2 receptor did not increase. IL 2 alone also induced proliferation of PBMC depleted of accessory cells, with the same kinetics but reduced peak response. Both accessory cells and supernatants that showed IL 1 but not IL 2 activity augmented this proliferation 50 to 100%. In contrast to the effect of IL 2, 25 to 50% of PBMC stimulated by PHA expressed an IL 2 receptor after 24 hr of culture. PHA-induced proliferation and IL 2 receptor expression peaked early in the culture period (routinely to 100,000 cpm and 50% respectively within 3 days), and colchicine did not inhibit the early induction of IL 2 receptors on PBMC. Our findings indicate that unlike PHA, IL 2 induces proliferation of PBMC (or PBMC depleted of accessory cells) by expanding the small percentage of cells in a resting population that already express IL 2 receptors. IL 2 does not appear to induce IL 2 receptors on cells previously lacking this molecule. We also find that IL 1 can enhance the response to IL 2 alone.

Antigen-Presenting Cells↗
PubMed1986

Nontuberculous mycobacterial infection in AIDS: clinical, pathologic, and radiographic features.

The medical records, radiographs, and pathologic specimens of ten patients with the diagnoses of nontuberculous mycobacterial infection and acquired immunodeficiency syndrome (AIDS) were examined. The radiographic findings of alveolar or nodular infiltrates and adenopathy were relatively nonspecific but in most cases led to bronchoscopic study or open-lung biopsy, which established the diagnosis. Bronchoscopic washings or sputum cultures, which frequently provided the first confirmation of infection, were always followed by positive blood or tissue cultures. In contrast to nontuberculous infection in immunocompetent hosts, disseminated infection was common, with evidence of extrapulmonary involvement in nine patients. On the basis of these findings, we recommend that any AIDS patient with sputum or bronchoscopic washings demonstrating nontuberculous mycobacterial organisms be tentatively classified as having disseminated infection while being evaluated with blood, bone-marrow, stool, and urine cultures, even if the chest radiograph shows no disease.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Accessory cells provide more than one signal for lectin mitogen-stimulated proliferation of human lymphocytes.

A culture system was developed in which human peripheral blood mononuclear cells (PBMC) depleted of Ia-expressing cells did not proliferate in response to the lectin mitogen phytohemagglutinin (PHA). These cells were able to respond to mitogen if purified autologous accessory cells were added back to the culture, thus showing an absolute requirement for Ia-expressing accessory cells in mitogen-driven T-cell proliferation. The identity of these accessory cells was shown to be not only monocytes but also Ia-expressing B cells and possibly other unidentified Ia-bearing cell types. Human interleukin-1 (IL-1) in the lectin mitogen-unresponsive culture system was found unable to reconstitute normal human T-cell proliferation. This suggests that those cells with Ia surface antigen acting as accessory cells must deliver more than an IL-1 signal for T-cell proliferation. The phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) was tested for its ability to replace necessary Ia-expressing accessory cells. TPA was able to replace accessory cells in culture, thus mimicking the Ia-expressing accessory cells and all their delivered signals in the triggering of human lymphocytes.

Antigen-Presenting Cells↗
PubMed1985

Changes in plasma histamine concentration in the streptozotocin-diabetic rat.

Plasma histamine concentrations were measured in rats made diabetic via jugular vein injection of streptozotocin and held 4 weeks following diabetes diagnosis. At least 15 diabetic animals received insulin (6-8 U/day) or alpha-hydrazinohistidine (alpha-HH) for the last week of the holding period. alpha-HH is a specific inhibitor of histidine decarboxylase (HD), the principle histamine-forming enzyme in mammals. Plasma histamine concentrations, expressed as means and mean standard errors (ng/ml) were as follows: control, 25.5 +/- 2.4; diabetic, 47.1 +/- 5.2; diabetic-insulin, 34.6 +/- 2.9; diabetic-alpha-HH, 28.1 +/- 2.1. These data indicate that in experimental diabetes there is an expansion of the nascent, or inducible histamine pool, an increase which is reflected by increased circulating plasma histamine. This may be one component mediating altered microvessel as well as large vessel permeability characteristics, an underlying component of both diabetic microangiopathy and macroangiopathy.

Animals↗
PubMed1985

Expanding spectrum of pulmonary disease caused by nontuberculous mycobacteria.

The clinical and radiographic features of 35 patients with nontuberculous mycobacterial (NTMB) pulmonary infections were reviewed. Radiographs of half the patients showed the pattern of cavitary upper-lobe infiltrates typical of reactivation tuberculosis; those of the other half had a radiographic pattern characterized by patchy, nodular infiltrates without an upper-lobe prevalence. Approximately half of the latter group showed multiple small cavities resembling those seen in bronchiectasis. These results suggest that studies in which the diagnosis of NTMB infection has been made primarily from sputum cultures may have been biased toward detecting cavitary disease. The spectrum of pulmonary disease caused by NTMB appears to be larger than previously appreciated. An enhanced awareness of alternate presentations of NTMB infections may result in earlier diagnosis.

Adult↗
PubMed1984

Time-dependent changes in aortic albumin permeability characteristics in experimental diabetes.

The aortic albumin flux, mass transport rates, and aortic albumin-plasma ratios were examined at 20, 30, and 60 min following injection of bovine serum albumin conjugated to fluorescein isothiocyanate (FITCBSA) in rats made diabetic via streptozotocin injection (65 mg/kg, jugular vein, ether anesthesia). These studies were undertaken in order to establish some basic semiquantitative permeability parameters of large arteries in experimental diabetes. Data indicate that under diabetic conditions, both the aortic flux and the mass transfer rates are significantly elevated, changes which correspond to increased tissue accumulation of FITCBSA. In addition, the time needed to saturate the albumin space in aortas of diabetic animals is significantly lower than normal.

Animals↗
PubMedDate not supplied

Use of neuroendocrine markers, p53, and HER2 to predict response to chemotherapy in patients with stage III non-small cell lung cancer: a Cancer and Leukemia Group B study.

Several studies have suggested that non-small cell lung cancer (NSCLC) patients whose tumors have neuroendocrine (NE) features may be more responsive to chemotherapy. In addition, increased expression of p53 and HER2 may confer relative chemotherapy resistance and shortened survival. The Cancer and Leukemia Group B performed a series of studies involving sequential chemotherapy followed by radiation for patients with unresectable stage III NSCLC. The objectives of this study were to analyze pathological specimens using immunohistochemistry for NE markers, p53 and HER2 to determine if there was a correlation between marker expression and response or survival. Of 160 eligible patients, 28 (18%) were not evaluable because of inadequate material. The percentage of specimens positive for markers was as follows: neuron-specific enolase 38%, Leu-7 2%, chromogranin A 0%, synaptophysin 5%, > or =2+NE markers 3%, p53 61%, and HER2 65%. There was no statistically significant correlation between any individual marker and response to induction chemotherapy or response to combined chemotherapy/radiation except for synaptophysin. Six of 6 (100%) synaptophysin positive tumors responded by the completion of all therapy compared with 69/125 (55%) synaptophysin negative tumors (P=0.04). None of the individual markers had a significant effect on survival in univariate analysis. Neuron-specific enolase was marginally significant in multivariate analysis (P=0.08). In conclusion, this study did not demonstrate that expression of NE markers, p53 and HER2 were predictive of response to chemotherapy, combined chemotherapy/radiation or for survival in this group of patients with stage III NSCLC. Future studies must employ either different markers or be performed on more adequate surgical specimens.

Antineoplastic Agents↗
PubMedDate not supplied

Application of solution equilibrium analysis to in vitro RNA transcription.

Solution equilibrium analysis of in vitro RNA transcription has been applied to examine changes in pH, free magnesium concentration, and concentrations of all chemical ionization species as a transcription reaction proceeds. With this method, the progress of a transcription reaction can be accurately determined as a function of measured pH. In addition, it is demonstrated that this method has significant value as a tool for achieving improved understanding of the effects of varying solution conditions on the dynamics of RNA transcription. Magnesium concentration was found to be a critical factor for efficient transcription. Below 5 mM free Mg2+ concentration, the transcription rate and the efficiency at which nucleoside triphosphates (NTPs) are incorporated are greatly reduced. While inorganic pyrophosphate (PPi), a byproduct of the reaction, was found to directly inhibit the rate of transcription, its detrimental effects on transcription were determined to be primarily due to sequestering of magnesium. The PPi forms a precipitate with magnesium which was determined to have a molar composition of 2:1 of Mg:PPi. Transcription rate and efficiency of NTP incorporation are also reduced with increasing ionic strength. It is shown that these reductions can be partially alleviated by replacing chloride with acetate anions.

Base Sequence↗
PubMedDate not supplied

Application of a fed-batch system to produce RNA by in vitro transcription.

A novel fed-batch method is presented for the production of RNA by in vitro transcription performed in a stirred-cell reactor with pH-controlled addition of reaction components. Solution equilibrium analysis is applied to determine the ratios of feed components (including nucleoside triphosphates (NTPs), magnesium salt, and base) which allow the desired NTP concentrations, free magnesium concentration, and pH to be maintained during the reaction. Results are presented for fed-batch and batch reactions performed with two DNA templates encoding a 12mer RNA and a 38mer RNA. For the dodecamer RNA, the fed-batch mode is only modestly better than batch reactions, with no significant increase in the efficiency of NTP incorporation but with 40% improvement in the amount of RNA produced per unit of polymerase or DNA. For the 38mer, fed-batch transcription provides a substantial increase in the efficiency of NTP incorporation and 100% improvement in the production of RNA per unit of polymerase or DNA. Cost analyses are presented which show how optimal NTP concentrations in batch and fed-batch reactions will be dependent on the relative costs of NTPs, T7 RNA polymerase, and DNA templates for the particular application. The use of a fed-batch mode appears to have the potential for substantial improvement in the economics of RNA production for at least some RNA sequences.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Neuregulin receptor-mediated gene transfer by human epidermal growth factor receptor 2-targeted antibodies and neuregulin-1.

The human epidermal growth factor receptors 2, 3, and 4 (HER2, HER3, and HER4, respectively) are frequently overexpressed in many human cancers, and therefore may be potential targets for receptor-mediated gene transfer. To evaluate this possibility, we constructed a series of HER-targeted gene transfer vehicles by covalently linking poly-L-lysine polymers (pLYS) to the epidermal growth factor-like domain of the HER ligand neuregulin-1 (NRG1(177-244)), a HER2 antibody (Ab), and the Fab fragment of the HER2 Ab. In vitro, pLYS modification of NRG1(177-244) decreased the affinity of the ligand for HER3 or HER4 homodimer receptors by 6- to 7-fold. DNA loading of the pLYS-modified NRG1(177-244) had a minimal additional affect on the affinity of the complex for its receptor. In cell lines engineered to solely express HER2, HER3, or HER4, each vehicle correctly targeted the receptors; the NRG1(177-244) construct transferred a luciferase gene only into cells expressing HER4, whereas the HER2 Ab and Fab constructs transferred the reporter gene only into cells expressing HER2. The most efficient gene transfer occurred using the intact HER2 Ab as a gene transfer vehicle, whereas the Fab fragment of the HER2 Ab was the least efficient, and NRG1(177-244) was intermediate. These studies suggest that the NRG receptor or HER2, a component of the receptor, can be pursued as targets for gene transfer.

Antibodies, Monoclonal↗
PubMedDate not supplied

Mercaptopurine-induced fever in a patient with Crohn's disease.

OBJECTIVE: To report a case of mercaptopurine-induced fever. CASE SUMMARY: A patient with Crohn's disease was treated with mercaptopurine (6-MP) for an exacerbation of his illness. The patient developed fever and chills. After thorough diagnostic examinations and failure to respond to antimicrobial therapy, symptoms were attributed to an allergic-type reaction to 6-MP. The patient defervesced after 6-MP withdrawal. Fever and chills, along with arthralgias, recurred upon rechallenge with a single dose of 6-MP. DISCUSSION: Adverse effects attributable to 6-MP therapy in inflammatory bowel disease were reviewed in the literature. Drug-induced fever has been previously reported; however, it is an uncommon adverse effect and is difficult to diagnose. It is also difficult to predict which patients will have the reaction. It is a diagnosis of exclusion requiring a thorough investigation. CONCLUSIONS: Drug-induced fever should be considered when confronted with fever and chills in patients with inflammatory bowel disease being treated with 6-MP. This case report shows the difficulty in differentiating between an infectious process and an adverse reaction to a medication.

Crohn Disease↗
PubMedDate not supplied

Carotid arteriography impacts carotid stenosis management.

Recent literature advocates carotid endarterectomy on duplex alone. The authors hypothesized that carotid angiography adds information that alters clinical management in a substantial number of patients compared to the use of carotid duplex examination alone. The records of 182 consecutive patients who underwent carotid artery duplex and subsequent carotid/cerebral angiography for suspected carotid artery stenosis between January 1998 and April 1999 were reviewed retrospectively. Carotid artery duplex examinations were stratified based on stenosis: < or =39%, 40% to 59%, 60% to 79% (moderate), 80% to 99% (severe), 100%. Carotid stenosis on angiograms was determined by NASCET criteria. New information found at angiography included vertebral, subclavian, or arch atherosclerosis, intracranial pathosis, or a change in duplex stenosis category to a degree of stenosis not requiring surgery. Clinical importance was attributed to angiograms that altered the patients' management plan. Angiography provided additional information in 53% (97/182) of patients. Vertebral disease was found in 25.1%, subclavian disease in 16.4%, intracranial disease in 15.3%, aortic arch disease in 3.3%. Patient treatment was altered in 30% (55/182). Angiographic findings downgraded the stenosis to medical therapy in 20.9% (38/182). The surgical plan was influenced in 5.5% (10/182). Nine intracranial aneurysms were discovered. Carotid angiography was essential for vascular bypass surgery planning in 3.3% (6/182). Angioplasty was performed in 2.2% (4/182). The accurate determination of stenosis is critical in determining optimal treatment of patients with carotid artery stenosis. Routine carotid angiography remains valuable in the clinical treatment of these patients.

Aged↗
PubMedDate not supplied

Denervation of the immature porcine lung impairs normal airway development.

Reimplantation or allotransplantation of the immature porcine left lower lobe results in long-term functional dynamic airway obstruction that is associated with abnormally small distal airways. We have attributed this small airway size to bronchoconstriction resulting from chronic denervation rather than to impaired airway growth. To further investigate these findings, we transplanted mature left lower lobes from adult pigs into young piglets after left pneumonectomy. After approximately 12 weeks of somatic growth, the lobes were harvested and fixed through the airways with formalin. Cross-sectional areas of terminal, noncartilaginous airways from the lung periphery were traced on a video monitor. Five groups were examined: control innervated mature left lower lobes, innervated left lower lobes subjected to compensatory growth after left upper lobectomy at approximately 9 weeks of age, mature left lower lobe transplants, reimplanted immature left lower lobe autografts, and transplanted immature left lower lobe allografts. Unlike the immature porcine lobe, transplantation of the mature porcine lobe does not result in abnormally small airways. The small airways seen after transplantation or reimplantation of the immature porcine lobe are likely, therefore, to be due to impaired airway development and not to bronchoconstriction caused by denervation.

Age Factors↗