Characterization of process air emissions in automotive production plants.

During manufacturing, particles produced from industrial processes become airborne. These airborne emissions represent a challenge from an industrial hygiene and environmental standpoint. A study was undertaken to characterize the particles associated with a variety of manufacturing processes found in the auto industry. Air particulates were collected in five automotive plants covering ten manufacturing processes in the areas of casting, machining, heat treatment and assembly. Collection procedures provided information on air concentration, size distribution, and chemical composition of the airborne particulate matter for each process and insight into the physical and chemical processes that created those particles.

Underexpression of beta cell high Km glucose transporters in noninsulin-dependent diabetes.

The role of defective glucose transport in the pathogenesis of noninsulin-dependent diabetes (NIDDM) was examined in Zucker diabetic fatty rats, a model of NIDDM. As in human NIDDM, insulin secretion was unresponsive to 20 mM glucose. Uptake of 3-O-methylglucose by islet cells was less than 19% of controls. The beta cell glucose transporter (GLUT-2) immunoreactivity and amount of GLUT-2 messenger RNA were profoundly reduced. Whenever fewer than 60% of beta cells were GLUT-2-positive, the response to glucose was absent and hyperglycemia exceeded 11 mM plasma glucose. We conclude that in NIDDM underexpression of GLUT-2 messenger RNA lowers high Km glucose transport in beta cells, and thereby impairs glucose-stimulated insulin secretion and prevents correction of hyperglycemia.

GLUT-2 function in glucose-unresponsive beta cells of dexamethasone-induced diabetes in rats.

Spontaneous and dexamethasone-induced noninsulin-dependent diabetes mellitus (NIDDM) in rats is associated with loss of glucose-stimulated insulin secretion (GSIS) and a reduction in both GLUT-2-positive beta cells and high Km glucose transport. To determine if the chronology and correlation of these abnormalities is consistent with a causal relationship, Zucker (fa/fa) rats were studied longitudinally before and during 10 d of dexamethasone-induced (0.4 mg/kg per d i.p.) NIDDM. Within 24 h of dexamethasone treatment blood glucose rose and GSIS declined, becoming paradoxically negative (-87 +/- 12 microU/ml per min) on day 10. Blood glucose was negatively correlated with GSIS (r = -0.92; P < 0.001). 3-0-methyl-D-glucose (3MG) transport was unchanged at 12 h, 23% below normal on day 1, and declined further to a nadir 59% below normal. The GLUT-2-positive beta cell area did not decline until 48 h, reaching a nadir of 35% of normal at 10 d. The area of GLUT-2-positive beta cells was correlated with GSIS (r = 0.77; P < 0.005). We conclude that the chronology and correlation between GSIS loss and hyperglycemia is consistent with a cause-effect relationship, but that the subtotal impairment in glucose transport by itself cannot explain the total loss of GSIS if one assumes that normal beta cells are functionally homogenous.

Muscle cell electrical hyperpolarization and reduced exercise hyperkalemia in physically conditioned dogs.

Contracting muscle cells release K ions into their surrounding interstitial fluid, and some of these ions, in turn, enter venous plasma. Thereby, intense or exhaustive exercise may result in hyperkalemia and potentially dangerous cardiotoxicity. Training not only reduces hyperkalemia produced by exercise but in addition, highly conditioned, long-distance runners may show resting hypokalemia that is not caused by K deficiency. To examine the factors underlying these changes, dogs were studied before and after 6 wk of training induced by running on the treadmill. Resting serum [K] fell from 4.2 +/- 0.2 to 3.9 +/- 0.3 meq/liter (P less than 0.001), muscle intracellular [K] rose from 139 +/- 7 to 148 +/- 14 meq/liter (P less than 0.001), and directly measured muscle cell membrane potential (Em) in vivo rose from -92 +/- 5 to -103 +/- 5 mV (P less than 0.001). Before training, resting Em of isolated intercostal muscle in vitro was -87 +/- 5 mV, and after incubation in 10(-4) M ouabain, Em fell to -78 +/- 5 mV. After training, resting Em of intercostal muscle rose to -95 +/- 4, but fell to -62 +/- 4 mV during incubation in 10(-4) M ouabain. The measured value for the Em was not completely explained by the increased ratio of intracellular to extracellular [K] or by the potassium diffusion potential. Skeletal muscle sarcolemmal Na,K-ATPase activity (microM inorganic phosphate mg-1 protein h-1) increased from 0.189 +/- 0.028 to 0.500 +/- 0.076 (P less than 0.05) after training, whereas activities of Mg2+ -dependent ATPase and 5'nucleotidase did not change. In untrained dogs, exercise to the point of exhaustion elevated serum [K] from 4.4 +/- 0.5 to 6.0 +/- 1.0 meq/liter (P less than 0.05). In trained dogs, exhaustive exercise was associated with elevation of serum [K] from 3.8 +/- 0.3 to 4.2 +/- 0.4 (NS). The different response of serum [K] to exercise after training was not explainable by blood pH. Basal insulin levels rose from 7.0 +/- 0.7 microU/ml in the untrained dogs to 9.9 +/- 1.0 microU/ml (P less than 0.05) after training. Although insulin might have played a role in the acquired electrical hyperpolarization, the reduced exercise-produced hyperkalemia after training was not reversed by blockade of insulin release with somatostatin. Although the fundamental mechanisms underlying the cellular hyperpolarization were not resolved, our observations suggest that increased Na-K exchange across the sarcolemmal membrane, the increase of Na,K-ATPase activity and possibly increased electrogenicity of the sodium pump may all play a role in the changes induced by training.

The tissue distribution of tumor necrosis factor biosynthesis during endotoxemia.

Tumor necrosis factor (TNF) is a protein hormone implicated in the development of septic shock and other pathologic states. However, complexities inherent in detecting TNF synthesis by individual tissues have left the precise origins of this protein undefined. In addition, the possibility that localized TNF production may contribute to the pathogenesis of organ-specific diseases such as type I diabetes has not been explored in vivo. We have developed a transgenic mouse line bearing a reporter gene construct in which the TNF coding sequence and introns are replaced by a chloramphenicol acetyltransferase (CAT) coding sequence. In normal transgenic animals, CAT activity is expressed only in the thymus. When endotoxin is administered to the animals, CAT activity is also evident in kidney, heart, islets of Langerhans, spleen, lung, fallopian tubes, and uterus, but not in other organs. The biosynthesis of CAT in vivo correlated with tissue capacity to secrete TNF in vitro. Thus, TNF was secreted by all the tissues that expressed CAT, including lung, spleen, thymus, uterus/fallopian tubes, pancreatic islets, renal glomeruli, and cultured cardiac cells after exposure to endotoxin.

Roles of insulin resistance and beta-cell dysfunction in dexamethasone-induced diabetes.

The roles of insulin resistance and beta-cell dysfunction in glucocorticoid-induced diabetes were determined in Wistar and Zucker (fa/fa) rats. All Wistar rats treated with 5 mg/kg per d of dexamethasone for 24 d exhibited increased beta-cell mass and basal and arginine-stimulated insulin secretion, indicating insulin resistance, but only 16% became diabetic. The insulin response to 20 mM glucose was normal in the perfused pancreas of all normoglycemic dexamethasone-treated rats but absent in every diabetic rat. Immunostainable high Km beta-cell transporter, GLUT-2, was present in approximately 100% of beta-cells of normoglycemic rats, but in only 25% of beta cells of diabetic rats. GLUT-2 mRNA was not reduced. All Zucker (fa/fa) rats treated with 0.2-0.4 mg/kg per d of dexamethasone for 24 d became diabetic and glucose-stimulated insulin secretion was absent in all. High Km glucose transport in islets was 50% below nondiabetic controls. Only 25% of beta cells of diabetic rats were GLUT-2-positive compared with approximately 100% in controls. Total pancreatic GLUT-2 mRNA was increased twofold suggesting a posttranscriptional abnormality. We conclude that dexamethasone induces insulin resistance, whether or not it induces hyperglycemia. Whenever hyperglycemia is present, GLUT-2-positive beta cells are reduced, high Km glucose transport into beta cells is attenuated and the insulin response to glucose is absent.

Demonstration of human pancreatic anionic trypsinogen in normal serum by radioimmunoassay.

A specific radioimmunoassay for human pancreatic anionic trypsin has been developed. The trypsin employed as radioiodinated tracer in the assay was inactivated with tosyl-L-lysine chloromethyl ketone in order to prevent binding of the tracer to the serum inhibitors alpha1-antitrypsin and alpha2-macroglobulin. A normal serum level of immunoreactive anionic trypsin of 5.45 ng/ml was determined. The results of experiments in which serum was fractionated by Sephadex G-200 gel filtration suggest that essentially all of the immunoreactive material in normal human serum is trypsinogen. This finding implies that a small fraction of the zymogens synthesized in the pancreas are released directly into the circulation.

STZ transport and cytotoxicity. Specific enhancement in GLUT2-expressing cells.

The glucose analog streptozotocin (STZ) has long been used as a tool for creating experimental diabetes because of its relatively specific beta-cell cytotoxic effect, but the mechanism by which systemic injection of STZ causes beta-cell destruction is not well understood. In the current study, we have used insulinoma (RIN) and AtT-20ins cell lines engineered for overexpression of GLUT2 or GLUT1 to investigate the role of glucose transporter isoforms in mediating STZ cytotoxicity. The in vivo effects of STZ were evaluated by implantation of RIN cells expressing or lacking GLUT2 into athymic nude rats. The drug had a potent cytotoxic effect on RIN cells expressing GLUT2, but had no effect on cells lacking GLUT2 expression, as indicated by histological analysis and measurement of the blood glucose levels of treated animals. The preferential cytotoxic effect of STZ on GLUT2-expressing cell lines was confirmed by in vitro analysis of GLUT2-expressing and untransfected RIN cells, as well as GLUT2- and GLUT1-overexpressing AtT-20ins cells. Consistent with these data, only GLUT2-expressing RIN or AtT-20ins cells transported STZ efficiently. We conclude that expression of GLUT2 is required for efficient killing of neuroendocrine cells by STZ, and this effect is related to specific recognition of the drug as a transported substrate by GLUT2 but not GLUT1.

GLUT2 expression and function in beta-cells of GK rats with NIDDM. Dissociation between reductions in glucose transport and glucose-stimulated insulin secretion.

GLUT2 underexpression has been reported in the beta-cells of Zucker diabetic fatty rats and db/db mice, models of spontaneously occurring NIDDM with antecedent obesity. To determine whether the beta-cells of a nonobese rodent model of NIDDM exhibit the same abnormalities in GLUT2, we studied Goto-Kakizaki rats. In these mildly diabetic animals glucose-stimulated insulin secretion was reduced at all ages examined from 8 to 48 wk. In normal control Wistar rats, immunostainable GLUT2 was present on all insulin-positive cells in the pancreatic islets. Only 85% of beta-cells were GLUT2-positive in GK rats at 12 wk of age, and only 34% were positive at 48 wk of age. GLUT2 mRNA was 50% of normal in 12-wk-old GK rats. In the latter age-group, glucose-stimulated insulin secretion was only 28% of normal at a time when 85% of beta-cells were GLUT2-positive and initial 3-O-methyl-D-glucose transport rate was 77% of the control value. We conclude that although GLUT2 is underexpressed, neither the magnitude of the underexpression of GLUT2 nor of the reduction in GLUT2 transport function in islets of GK rats is sufficient by itself to explain the profound reduction in glucose-stimulated insulin secretion.

Identification of a peptide toxin from Grammostola spatulata spider venom that blocks cation-selective stretch-activated channels.

We have identified a 35 amino acid peptide toxin of the inhibitor cysteine knot family that blocks cationic stretch-activated ion channels. The toxin, denoted GsMTx-4, was isolated from the venom of the spider Grammostola spatulata and has <50% homology to other neuroactive peptides. It was isolated by fractionating whole venom using reverse phase HPLC, and then assaying fractions on stretch-activated channels (SACs) in outside-out patches from adult rat astrocytes. Although the channel gating kinetics were different between cell-attached and outside-out patches, the properties associated with the channel pore, such as selectivity for alkali cations, conductance ( approximately 45 pS at -100 mV) and a mild rectification were unaffected by outside-out formation. GsMTx-4 produced a complete block of SACs in outside-out patches and appeared specific since it had no effect on whole-cell voltage-sensitive currents. The equilibrium dissociation constant of approximately 630 nM was calculated from the ratio of association and dissociation rate constants. In hypotonically swollen astrocytes, GsMTx-4 produces approximately 40% reduction in swelling-activated whole-cell current. Similarly, in isolated ventricular cells from a rabbit dilated cardiomyopathy model, GsMTx-4 produced a near complete block of the volume-sensitive cation-selective current, but did not affect the anion current. In the myopathic heart cells, where the swell-induced current is tonically active, GsMTx-4 also reduced the cell size. This is the first report of a peptide toxin that specifically blocks stretch-activated currents. The toxin affect on swelling-activated whole-cell currents implicates SACs in volume regulation.

Daily stress and recurrence of genital herpes simplex.

It is widely believed that emotional stress triggers recurrences of both oral and genital herpes simplex virus. On a daily basis, we studied 64 subjects prospectively for 1 to 3 months; all subjects had at least one culture-proved recurrence of genital herpes simplex virus type 2 before or during the study. All subjects filled out a questionnaire that measured psychological/emotional stress in six areas: physical health, relations with friends, relations with family, relations with sex partner(s), financial, and vocation/education. These questionnaires were mailed back to us daily. Data were analyzed by General Linear Models analysis of variance to compare stress reported on each of the 6 days before a recurrence with that on days during or after a recurrence, as well as days not temporally related to recurrence. Under these conditions, in which retrospective bias was minimized, there was no significant increase in psychological/emotional stress on any day in any area preceding a recurrence of genital herpes simplex virus.

Serotonergic mediation of a negative feedback effect of estrogen on luteinizing hormone release in ovariectomized rats.

Effects of the serotonin receptor antagonists ketanserin, metergoline, and methysergide on LH release were tested in ovariectomized (OVX) rats pretreated with estradiol benzoate (EB) (5 micrograms/100 g BW) on each of the 2 days preceding the experiment. LH concentration measured by RIA in plasma samples obtained at 10 min intervals was analyzed using the PULSAR computer program to identify and characterize pulses observed in the LH profile of each rat individually. Multiple pulses were identified in seven of seven OVX rats but in only two of eight OVX rats primed with EB. Multiple pulses were identified in OVX EB-primed rats pretreated with ketanserin (six of seven), metergoline (three of seven), and methysergide (six of eight). Administration of the serotonin (5HT) agonist quipazine (2 mg/kg iv) to OVX rats inhibited pulsatile LH release and depressed mean plasma concentrations for approximately 45 min. This inhibitory response was antagonized by pretreatment of the OVX animals with ketanserin. These results suggest that 1) quipazine inhibits pulsatile LH release in OVX rats by a serotonin2 receptor mechanism; and 2) the inhibitory effect of estrogen on pulsatile LH release may also be mediated, at least in part, via 5HT2 systems.

Opiate-serotonin synergism stimulating luteinizing hormone release in estrogen-progesterone-primed ovariectomized rats: mediation by serotonin2 receptors.

A tonic inhibition of LH release by endogenous opiate systems is apparent after administration of opiate antagonists to ovariectomized estrogen-progesterone-primed rats. In the presence of a serotonin agonist, morphine has been found to stimulate LH release in ovariectomized animals. Thus, in the present study the individual effects as well as interactions of the opiate and serotonin (5HT) systems have been examined using morphine and quipazine, respectively, as agonists and ketanserin (5HT2) and methysergide (5HT1 and 5HT2) as antagonists. Rats ovariectomized 2-4 weeks beforehand were primed with estradiol benzoate (15 micrograms; day 0) and progesterone (5 mg; day 2). Serial blood samples were collected from unrestrained rats via a jugular cannula inserted 3 days before, and plasma LH was measured by RIA. Neither morphine (4 mg sulfate) nor quipazine (2 mg/kg) administered iv at 1200 h significantly elevated plasma LH at 1210, 1220, or 1230 h compared to levels at 1200 h, although plasma LH concentrations at these times were significantly greater than those in animals receiving saline at 1200 h. However, injection of both morphine and quipazine at 1200 h greatly augmented LH release at 1210, 1220, and 1230 h compared to the response to either drug alone. The duration of the significant elevation of plasma LH was limited to 10 min by ketanserin (2.5 mg/kg, ip, at 0900 h) and to 20 min by methysergide (10 mg/kg, ip, at 0900 h), suggesting mediation of this response by 5HT2 receptors. These results suggest the possibility of an important interaction between opiate and serotonergic systems in controlling the release of LH and raise the intriguing question of its role, if any, in controlling events of the estrous cycle.

Growth hormone (GH) secretion in the pituitary-grafted male rat: in vivo effects of GH-releasing hormone and isoproterenol and in vitro release by individual somatotropes.

Although the pituitary-grafted rat is a classic model of chronic PRL excess, the presence of somatotropes in grafted pituitary tissue indicates a potential for GH secretion. The current study was designed to investigate GH-releasing hormone (GRH)-induced GH secretion and beta-adrenergic inhibition of GH release in animals bearing ectopic pituitary tissue free from hypothalamic control. Positive findings with regard to these in vivo experiments led us to an initial determination of GH secretion by individual somatotropes from transplanted pituitary tissue. In litters of 10 30-day-old Fisher rats, 2 male animals received subcapsular renal grafts of 3 littermate pituitary glands each. Thirty-five days after grafting, 1 group received saline (SAL) followed by GRH, and the other received the beta-adrenergic agonist isoproterenol (ISO) followed by GRH. Blood samples were taken before and after SAL or ISO treatment, GRH was then infused, and sampling was continued. Plasma was assayed for GH and PRL, and the reverse hemolytic plaque assay was used to determine GH release by individual somatotropes from transplanted pituitary tissue. Plasma PRL was clearly elevated in pituitary-grafted compared to muscle-grafted animals, but there was no difference in either body weight gain or basal GH levels between the groups. As shown previously, ISO itself induced a brief release of GH due to its direct effect on the pituitary gland. The GH response to GRH was greater in pituitary-grafted animals than in muscle-grafted controls after both SAL and ISO. GRH-induced GH release was suppressed by ISO pretreatment in muscle-grafted animals, but not in pituitary-grafted animals. The reverse hemolytic plaque assay unequivocally showed that transplanted pituitary tissue was capable of tonic as well as GRH-stimulated GH release. These results demonstrate that despite similar basal GH levels, animals bearing pituitary grafts release significantly greater amounts of GH in response to GRH. The evidence for GH secretion by individual somatotropes from transplanted pituitary tissue directly shows the grafted tissue to be a source of GRH-stimulated GH. The lack of beta-adrenergic inhibition of GRH-induced GH release in pituitary-grafted animals is consistent with the hypothesis that beta-adrenergic inhibition of GRH-induced GH secretion is mediated by an effect on the hypothalamus.

Beta-adrenergic stimulation of growth hormone (GH) release in vivo, and subsequent inhibition of GH-releasing factor-induced GH secretion.

In vivo and in vitro studies of beta-adrenergic influences on GH secretion have produced apparently conflicting data in which the in vivo effect seems to be inhibitory and the in vitro effect to be stimulatory. The present studies were designed to observe the in vivo effect of isoproterenol (ISO), a beta-adrenergic agonist, on 1) GH release during a brief interval after intraatrial infusion, and 2) GH release in response to GRF infused 10 min after ISO. ISO was found to stimulate GH release in both intact and hypothalamus-lesioned animals within 2 min after infusion, but GH returned to control levels within 10 min. ISO also profoundly inhibited the release of GH in response to GRF. Pretreatment of animals with somatostatin (SRIF) antiserum prevented the inhibitory action of ISO on GRF-induced GH release. No change in peripheral levels of SRIF was detected. Also, there was no suppression of GRF-induced GH release by ISO when the treatments were applied in vitro to dispersed perifused pituitary cells. These data show that beta-adrenergic systems can stimulate a rapid but brief release of GH in vivo, and that the subsequent inhibitory action on GRF-induced GH release might be by means of SRIF release.

A computer-assisted psychiatric assessment unit.

The authors discuss the rationale and functional design for an innovative approach to psychiatric intake decision making, stressing the crucial role of an on-line computer support system. The description of the prototype computer-assisted psychiatric assessment process includes an outline of computer and staffing requirements. The authors discuss the initial impact of this psychiatric assessment unit on the hospital's mental health care delivery system.

Flurbiprofen versus naproxen in the treatment of rheumatoid arthritis.

The efficacy and safety of flurbiprofen (Ansaid, Upjohn), 100 mg twice daily, were compared with those of naproxen, 250 mg twice daily, in a six-week, double-blind, randomized study involving 133 patients with rheumatoid arthritis. Patients completing the six-week treatment phase were then treated with flurbiprofen, 100 mg twice daily, during a six-week open-label phase. In the double-blind phase, both treatment groups showed improvement from baseline and, in general, the arthritic condition of all patients was significantly less severe while receiving treatment. In the open-label phase, the patients in whom therapy was switched from naproxen to flurbiprofen reported greater improvement compared with baseline than they did at the end of the double-blind phase. Statistically significant differences between medication groups were few. At weeks four and six, grip strength for the naproxen group increased from baseline by a marginal amount compared with the flurbiprofen group. Global evaluations of disease improvement by patients and physicians and proximal interphalangeal joint size showed trends in favor of flurbiprofen. In the double-blind phase, 29.4 percent of flurbiprofen-treated patients (n = 20) and 23.1 percent of naproxen-treated patients (n = 15) experienced side effects, most of which were gastrointestinal in origin. In the open-label phase, 81.0 percent of the patients (n = 87) satisfactorily completed the six weeks of flurbiprofen treatment. Based on this study, 100 mg of flurbiprofen administered twice daily was as effective as 250 mg of naproxen twice daily in the treatment of rheumatoid arthritis.

Double-blind comparison of flurbiprofen and sulindac for the treatment of osteoarthritis.

In this double-blind, randomized trial involving 143 patients with osteoarthritis of the hip and/or knee, the efficacy and safety of twice-daily dosing with flurbiprofen (Ansaid, Upjohn), which has a half-life of 5.5 hours, were compared with those of sulindac, which has a half-life of 7.8 hours. Patients were treated with flurbiprofen (50 mg orally twice a day) or sulindac (150 mg orally twice a day) for six weeks. Based on evaluations by both patients and physicians, there were no statistically significant differences between the two treatment groups in most of the efficacy parameters studied. In addition, there were no statistically significant differences between the two treatment groups in the incidence or type of side effects, which were primarily gastrointestinal in origin. This study indicates that flurbiprofen, taken as 50 mg twice daily, is equally as effective as 150 mg of sulindac twice a day in the treatment of osteoarthritis.

Comparison of two dosing schedules of flurbiprofen for patients with rheumatoid arthritis. Twice-daily versus four-times-a-day schedules.

A total daily dose of 200 mg of flurbiprofen (Ansaid, Upjohn) was administered either twice daily (100 mg BID) or four times daily (50 mg QID) to 143 patients with rheumatoid arthritis. Results of this 12-week, randomized, double-blind study showed statistically significant reductions in the number of swollen joints, number of affected joints, duration of morning stiffness, and 50-foot walk time in patients receiving either treatment regimen. Using standard statistical tests, no significant differences between regimens were found. Flurbiprofen treatment was rated as "excellent" or "good" by approximately half of the patients and physicians following both BID or QID dosing.

Carboxyimamidate, a low-molecular-weight polyelectrolyte with antitumor properties and low toxicity.

A new polyelectrolyte was synthesized and evaluated for antitumor activity. The product is a derivative of ethylene/maleic anhydride copolymer of low molecular weight (Mn approximately equal to 1100). The anhydride groups were first converted to the half-amide, half-ammonium salt by reaction with ammonia. A percentage (14-25 wt %) of these groups was further converted to the imide by heating. The product, carboxyimamidate (Carbethimer, N-137) inhibited the growth of a number of solid tumors in vivo. Sensitive tumor models included Lewis lung carcinoma, Madison 109 lung carcinoma, M5076 ovarian tumor, colon carcinoma 26, B16 melanoma, and P815 mastocytoma. Activity was dose related between nontoxic dose levels of 300 and 2000 mg/kg ip.