Continuous pump pressures cannot be used to identify catheter tip migration into the subarachnoid space

BACKGROUND AND OBJECTIVES

Migration of an epidural catheter into the subarachnoid space is a potentially lethal complication of continuous epidural anesthesia. We evaluated the use of pump pressure measurement during infusion in detecting such an occurrence.

METHODS

Pump pressures at two flow rates (P1 and P10) and epidural space pressure (P0) were measured hourly in eight consecutive ASA Physical Status I parturients receiving continuous epidural anesthesia and compared to those of a patient whose catheter migrated into the subarachnoid space. In addition, total resistance to infusion (Rtot) was calculated as the slope of the least squares regression line linking pressure and flow. Epidural resistance (Repi) was computed as the difference between total resistance and catheter resistance; Repi = Rtot - Rcath.

RESULTS

In epidural catheters, average P0 and P10 were 13 +/- 4 mmHg and 23 +/- 4 mm Hg, respectively, and did not change over time. Rtot and Repi averaged 960 +/- 180 RU and 980 +/- 120 RU, respectively. Pump pressures in the subarachnoid catheter were 10 mmHg for P0 and 20 mmHg for P10, while Rtot was 1000 RU.

CONCLUSIONS

We conclude that epidural and subarachnoid space resistance is essentially zero and the pump pressure in the system is used to overcome the catheter resistance. Both spaces offer the same total resistance to infusion and, therefore, pump pressure will not change when a catheter migrates into the subarachnoid space.

Transforming growth factor-beta and transforming growth factor beta-receptor expression in human meningioma cells

The transforming growth factor-beta (TGF beta) family in mammals includes three closely related peptides that influence proliferation and numerous physiologic processes in most mesenchymal cells. In this study, Northern blots, immunohistochemistry, TGF beta radioreceptor assays, TGF beta receptor affinity labeling and [3H] thymidine incorporation were used to evaluate whether primary cell cultures of human meningiomas synthesize the three TGF beta isoforms, bear TGF beta receptors, and respond to TGF beta. Transcripts for TGF beta 1 and 2 were detected in the three cases analyzed. Transforming growth factor-beta 1 immunoreactivity was detected in three of six cases, and TGF beta 2 and 3 immunoreactivity were detected in each case analyzed. Media conditioned by cells cultured from six meningiomas also contained latent TGF beta-like activity. Transforming growth factor-beta receptor cross-linking studies identified TGF beta binding sites corresponding to the type 1, type 2, and type 3 receptors on meningioma cells. Treatment with active TGF beta 1 produced a statistically significant reduction in [3H] thymidine incorporation after stimulation with 10% fetal calf serum and epidermal growth factor in all six cases studied.

Growth factors in breast cancer: mitogenesis to transformation

While endocrine steroid hormones have been known for many years to regulate normal and malignant mammary epithelium, recent studies have led to an appreciation of polypeptide growth factors as locally-acting autocrine and paracrine effectors. In the current article we summarize what is known about growth factor regulation and action in the normal mammary gland and about perturbations of the steroid-growth factor interplay as cancer progresses. A major theme is that oncogenic activation modulates both regulation of production and function of growth factors in the mammary gland.

Evidence for transforming growth factor-beta expression in human leptomeningeal cells and transforming growth factor-beta-like activity in human cerebrospinal fluid

BACKGROUND

Little is known about the factors regulating growth and maintenance of human leptomeningeal cells. The influence of cerebrospinal fluid on these functions is also unknown. Possible mediators include the transforming growth factor-beta (TGF beta) family, three closely related peptides that regulate proliferation and numerous other physiologic processes in most mesenchymal cells.

EXPERIMENTAL DESIGN

Expression of both mRNA and protein for TGF beta isoforms TGF beta 1, TGF beta 2, and TGF beta 3 as well as TGF beta-competing activity were evaluated in primary human leptomeningeal cultures by Northern blot analysis, immunohistochemistry, and a radioreceptor assay, respectively. TGF beta 1, TGF beta 2, and TGF beta 3 immunoreactivity was also evaluated in brain sections containing leptomeninges from which these cell cultures were established. An additional study analyzed human cerebrospinal fluid for TGF beta-like activity.

RESULTS

Transcripts for TGF beta 1, TGF beta 2 and TGF beta 3 were detected in RNA from each of the eight leptomeningeal cultures. Significant TGF beta 1 immunoreactivity was detected in leptomeningeal tissue from five of eight cases. TGF beta 2 and TGF beta 3 immunostaining was seen in eight and seven of the cases, respectively. Similarly, cells cultured from these meninges exhibited variable TGF beta 1 and extensive TGF beta 2 and TGF beta 3 immunoreactivity. Radioreceptor assays of conditioned media from four cultures demonstrated significant latent TGF beta-like activity. TGF beta radioreceptor competing activity was also detected by radioreceptor assay in normal blood-free cerebrospinal fluid from 32 patients without neurological disease. In addition, pooled cerebrospinal fluid (from six additional patients) exhibited dose dependent TGF beta-like activity in the radioreceptor assay, stimulation of AKR-2B cell growth in soft agar and inhibition of growth in CCL-64 cell assays suggesting that cerebrospinal fluid contains TG beta-like activity.

CONCLUSIONS

These findings suggest that the human leptomeninges synthesize TGF beta 1, TGF beta 2 and TGF beta 3 and secrete latent TGF beta s at least in vitro. Human cerebrospinal fluid may also contain TGF beta isoforms. Collectively, these observations raise the possibility that members of the TGF beta family contribute to biologic processes of the leptomeninges.

In vitro karyotypic and immunophenotypic characterisation of primitive neuroectodermal tumours: similarities to malignant gliomas

Monoclonal antibody (Mab) mediated immunotherapy of brain tumours requires the identification of tumour-restricted cell surface antigens. We have characterised four primitive neuroectodermal tumours, which included pineoblastoma, medulloblastoma and ependymoblastoma cultures, that demonstrated in vitro evidence of malignant behaviour (anchorage-independent growth and nu/nu xenograft tumour formation). The cytogenetic findings ranged from normal G-banded and Q-banded karyotypes through mixed near-diploid/hyperdiploid. These cultures resembled the cell surface immunophenotypic spectrum of malignant gliomas. They were distinguished from normal glia in vitro by the expression of restricted fetal mesenchymal, neuronal, myoblastic, melanocytic, epidermal, chondrocytic, lymphoid and epithelial antigens. Certain antigens appeared sufficiently represented among central nervous system (CNS) neoplasms to afford potential targets for Mab-mediated immunotherapy.

Age-related decrease in omega conotoxin binding to rat cardiac synaptosomes

A cardiac synaptosomal preparation developed by this laboratory was used to study neuronal calcium channels in aging rat heart. Ca2+ channels were quantified by measuring binding of iodinated omega conotoxin, which is reported to specifically block neuronal Ca2+ channels. We determined the binding of [125I]-omega conotoxin GVIA to a synaptosomal preparation from the hearts of 6- and 24-month-old male Fisher 344 rats. The maximum number of binding sites (Bmax +/- SD, fmol/mg protein) is lower in preparations from 24-month (2.2 +/- 0.6) than from 6-month (3.4 +/- 0.7)-old rats. This decrease in number of binding sites suggests an age-related reduction in the number of neuronal calcium channels. Since calcium is essential for exocytotic release of norepinephrine and is made available intracellularly through neuronal calcium channels, the reduction in neuronal calcium channel number may explain, in part, our previous observations of diminished release of norepinephrine in senescent hearts.

Effects of an opiate receptor antagonist on renin release in dogs

The present experiments were designed to determine whether blockade of endogenous opiate receptors with naloxone would suppress renin release induced by circulating epinephrine or by reductions of renal perfusion pressure. In the first series of experiments, anesthetized dogs were prepared with a flow probe around the left renal artery and a catheter in the left renal vein, permitting measurement of renin secretion before, during, and after 15-min infusions of epinephrine (50 ng.kg-1.min-1 iv). The epinephrine infusions were conducted either before or after blockade of opiate receptors with naloxone (1 mg/kg iv). Naloxone failed to alter the renin secretory response to intravenous epinephrine infusion. In a second series of experiments, anesthetized dogs were uninephrectomized and prepared with a constrictor cuff around the left renal artery and a renal arterial catheter distal to the cuff. After control measurements of renal perfusion pressure and plasma renin activity (PRA), the cuff was constricted at 15-min intervals to produce controlled stepwise reductions of renal perfusion pressure ranging from 15 to 90 mmHg. One-half of the animals was pretreated with naloxone (1 mg/kg iv). Naloxone pretreatment had no effect on the PRA response to reduced renal perfusion pressure at any pressure. The data fail to support the hypothesis that endogenous opioid peptides are modulators in the control of renin release.

Binding Constants for Cyclodextrin Inclusions by Competitive Spectrofluorometry Involving 6-(p-Toluidino)naphthalene-2-sulfonate

Binding constants of derivatized and simple β-cyclodextrins with a variety of inclusates were determined spectrofluorometrically through competition with 6-(p- toluidino )naphthalene- 2-sulfonate ( tns ). Inclusates in addition to tns were sodium alkane-1-sulfonates, sodium tetraphenylborate, sodium tetrafluoroborate, pyrazine and 4,4'-bipyridine.

Effect of naloxone on hypertension in Dahl salt-sensitive rats

Experiments were conducted to test the hypothesis that chronic administration of an opioid receptor antagonist, naloxone, would affect the outcome of the developmental phase of hypertension in Dahl salt-sensitive (S/JR strain) rats. Accordingly, S/JR rats were maintained on either a low-salt (0.45% NaCl) or a high-salt (7% NaCl) diet for 4 wk. Half of the animals of each dietary group were treated with naloxone (100-130 micrograms/h) by osmotic minipump. Food and water intakes of the high-salt animals were measured for the first 25 days, and blood pressure was measured at the end of the 4 wk via an indwelling femoral arterial catheter. Naloxone treatment slightly but significantly reduced the level of hypertension attained in the high-salt animals (158 +/- 2 mmHg in naloxone-treated animals vs. 168 +/- 3 mmHg in control animals; P less than 0.05) and also attenuated food (and hence salt) and water intakes. Naloxone did not affect the blood pressure of the low-salt animals. To determine whether the slight attenuation of hypertension might be secondary to a reduction of salt intake, a group of control S/JR animals were fed a moderately high-salt diet (2% NaCl), and naloxone-treated S/JR animals were salt-intake matched to this group by daily adjustment of the dietary salt content. Blood pressures after 4 wk of treatment were not different between these two groups. Finally, acute administration of 1 and 30 mg/kg of naloxone failed to lower blood pressure of animals with established hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of transforming growth factor-beta 1, -beta 2, and -beta 3 mRNA and protein in the murine lung

Evidence has accumulated suggesting that the various isoforms of beta-type transforming growth factors (TGF-beta s) regulate important functions in the lung; however, the cellular source of these proteins is not well defined. Northern blot analysis of murine lung tissue demonstrates that mRNA transcripts for all three TGF-beta isoforms are found from birth through adulthood. Although the level of expression for each TGF-beta is variable during the first 2 wk post partum, all three isoforms are equal in the adult lung. Using in situ hybridization and immunohistochemical analysis, we have localized both mRNA and protein expression for all three isoforms of TGF-beta in the adult murine lung. At low magnification, immunohistochemical localization of TGF-beta proteins appears coincident in their pattern of expression with TGF-beta mRNAs in the large proximal conducting airways of the lung. However, on closer analysis, protein expression of all three TGF-beta isoforms is confined to the bronchiolar epithelium, while TGF-beta mRNA transcripts for each of the TGF-beta genes are found in smooth muscle cells and connective tissue fibroblasts lying subjacent to the epithelium. Although the levels of both TGF-beta mRNA and protein expression are high in the proximal bronchiolar tree, their signal intensities completely disappear as the terminal bronchioles progress to respiratory bronchioles. Additionally, in the lung vasculature, there is very high expression of all three TGF-beta mRNA transcripts in the smooth muscle cells of the large vessels. TGF-beta2 and TGF-beta but not TGF-beta1 proteins are expressed in these same smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated content of the tyrosine kinase substrate phospholipase C-gamma 1 in primary human breast carcinomas

Phospholipase C-gamma 1 (PLC-gamma 1) is a substrate for several receptor tyrosine kinases and its catalytic activity is increased by tyrosine phosphorylation. However, the biological significance of this molecule in normal or malignant human epithelial cell proliferation is unknown. We determined the relative content of PLC-gamma 1 in primary human mammary carcinomas and in nonmalignant mammary tissues. By Western blot and immunohistochemistry, considerably higher levels of PLC-gamma 1 protein were detectable in the majority of carcinomas and in one of two benign fibroadenomas compared to normal breast tissues. In 18 of 21 carcinomas that contained high levels of PLC-gamma 1, the presence of phosphotyrosine on PLC-gamma 1 could also be detected. All carcinomas in which tyrosine phosphorylated PLC-gamma 1 was present also expressed detectable levels of the epidermal growth factor receptor or erbB-2, two tyrosine kinases known to phosphorylate this enzyme. Thus, a high percentage of mammary carcinomas concomitantly display increased levels of receptor tyrosine kinases and a direct tyrosine phosphorylation substrate, thereby potentially amplifying two successive steps in a signal transduction pathway.

Reduced G protein function in desensitized rat aorta

These studies investigated the role of G proteins in vascular desensitization. Rats were infused with norepinephrine (NE) subcutaneously (0.1 mg/kg/hr) for 6 days using osmotic minipumps and aortas were obtained. NE-stimulated contraction was blunted in aortas obtained from NE infused rats compared to aortas from vehicle infused controls. Contractile responses to KCl and serotonin (5-HT) were not affected by NE infusion indicating desensitization was specific to certain receptors. Dose response curves for NaF-stimulated contraction were right-shifted in aortas from NE infused rats suggesting reduced G protein function in these vessels. G protein function was studied further by assessing G protein activation in response to receptor stimulation. This was done by measuring agonist-stimulated increases in 35S-GTP gamma S binding to G protein alpha subunits in aortic membranes. The alpha 1 adrenergic agonist phenylephrine stimulated GTP tau S binding to Gs and Gi in aortic membranes and the degree of stimulation was reduced in desensitized vessels. 5-HT stimulated binding to Gi and Go in aortic membranes and the response was not altered in desensitized vessels. Thus, vascular desensitization produced by NE infusion involves selective reductions in the ability of alpha 1 receptors to activate Gs and Gi.

Phorbol diester-induced alterations in the expression of protein kinase C isozymes and their mRNAs. Analysis in wild-type and phorbol diester-resistant HL-60 cell clones

In an HL-60 cell subline (PR-17) which was greater than 100-fold resistant to the differentiating and cytostatic activities of phorbol 12-myristate 13-acetate (PMA), the protein kinase C phenotype was found to be nearly identical to that of wild-type HL-60 cells. A measurable decrease (30%) in the specific activities of crude preparations of PR-17 cell protein kinase C was observed when the enzyme was measured with histone as the phosphate acceptor substrate, but other aspects of the protein kinase C phenotype (intracellular concentrations and binding affinities of phorbol diester receptors, translocation of activated enzyme from cytosolic to particulate subcellular fractions, relative expression of the alpha and beta isozyme proteins) were equivalent in both PMA-resistant PR-17 cells and in wild-type HL-60 cells. Direct analysis of the behavior of the alpha and beta isozymes after the exposure of each cell type to 100 nM PMA for 12 h revealed that the activities and intracellular concentrations of both isozymes were downregulated to an equivalent extent in both wild-type and PMA-resistant cells. These results suggest that the cellular basis for the resistance to the effects of PMA was present "down-stream" from the activation and down-regulation of protein kinase C and was perhaps a nuclear component. Among the genes which were likely to be differentially regulated when each of the two cell lines were treated with PMA were those for the protein kinase C isozymes themselves. In wild-type HL-60 cells, the intracellular concentrations of type HL-60 cells, the intracellular concentrations of mRNA for each of the beta isozymes were increased (up to 5-fold) 48 h after the initiation of PMA treatment; further studies indicate that an activator of protein kinase C could influence the expression of HL-60 cell protein kinase C genes in an isozyme-specific manner. Comparable PMA-induced alterations in mRNA levels were not observed in PMA-resistant cells, even under conditions of significant activation and subsequent down-regulation of protein kinase C protein. Taken together, these data suggest that activation and down-regulation of the isozymes of protein kinase C may not represent absolute determinants of the PMA-induced differentiation of HL-60 cells, but that specific alterations in the levels of the mRNA for the beta isozymes of protein kinase C, or of other genes which may be regulated by the activated kinase isozymes, are important to the induction of leukemia cell differentiation by PMA.

Pressure-independent arteriolar rarefaction in hypertension

To assess the role of pressure in the arteriolar rarefaction associated with hypertension, we studied microvascular density in a hindquarters muscle (cremaster) of rats, 8 wk after coarctation (n = 8) or sham-coarctation (n = 10) of the abdominal aorta. To document the level of arterial pressure in hindquarters vascular beds of similar rats 8-9 wk after initial surgery, we implanted femoral arterial catheters under anesthesia and, 2-5 days later, we measured conscious femoral arterial pressures in coarcted [93 +/- 4 (SE) mmHg; n = 7] and sham-coarcted (110 +/- 3 mmHg; n = 4) rats. The cremaster muscle microcirculation was examined after fixation and Microfil infusion at in vivo pressures. The density of distal third- to fourth-order arterioles was lower by 19% (P = 0.03) in coarcted (1.37 +/- 0.06 mm/mm2) than in sham-coarcted (1.69 +/- 0.11 mm/mm2) rats. We conclude that pressure-independent mechanisms are involved in the arteriolar rarefaction accompanying hypertension.

Effect of age on presynaptic beta2 receptor mediated responses in the rat heart

Presynaptic alpha2 adrenergic receptor inhibition of norepinephrine (NE) release is diminished in older animals [1]. To determine whether presynaptic beta2 adrenergic receptor facilitation of NE release is also affected by age, the effect of propranolol on neurally-induced NE release was examined in perfused heart preparations isolated from 6- and 24-month-old rats. The heart was isolated with the right cardiac sympathetic nerve and then was stimulated electrically in the absence and presence of propranolol (10(-8)-10(-6) M). NE content in the effluent was measured by an HPLC/EC methodology. The data indicate that there is a greater suppression of NE release by propranolol in preparation isolated from younger animals. For example, in nerve-heart preparations of 6-month-old animals stimulated at 12 Hz, propranolol (10(-6) M) reduced the amount of NE released by 34% whereas in preparations from 24-month-old animals at 12 Hz there was no significant change in the NE overflow. Like the alpha2 receptor mechanism, autoregulation of NE release by presynaptic beta2 receptors is diminished in older animals. Lack of presynaptic autoregulation may explain in part, the reduced capacity of adrenergic influences to control and regulate cardiac function in older animals.

Alterations in cardiovascular responsiveness and adrenoceptor binding during catecholamine infusion hypertension in rats

Chronic continuous infusion of norepinephrine in rats causes alterations in biochemical and physiologic responses of the cardiovascular system and in cardiovascular adrenoceptor number. The response of cardiac and aortic ornithine decarboxylase (ODC) activity to stimulation by norepinephrine was decreased in rats receiving norepinephrine infusion. These responses are due to stimulation of beta- and alpha-adrenergic receptors, respectively. Additionally, there was reduced stimulation of aortic ODC activity by angiotensin II and vasopressin. The cardiac ODC response to angiotensin II was decreased, but the response to vasopressin was not affected. The decreased ODC response is accompanied by decreased pressor responses to the alpha-adrenergic agonist phenylephrine. Decreased numbers of alpha- and beta-adrenoceptor binding sites (as measured by the binding of [3H]prazosin and [125I]pindolol) might mediate, in part, the altered responses to adrenergic agonists. The decreased cardiovascular responsiveness measured in these animals after several days of norepinephrine infusion hypertension contrasts with the increased responses found in most other forms of hypertension. This provides a useful model in which to examine the consequences of prolonged adrenergic receptor stimulation.

Maternal and fetal plasma atrial natriuretic peptide concentrations during elective caesarean section

Atrial natriuretic peptide (ANP) is stored in the atrial cardiocyte and is capable of exerting potent, selective, and transient effects on fluid and electrolyte balance and on blood pressure. Because fluid shifts and hemodynamic adjustments occur during parturition, ANP might play a homeostatic role in the parturient and fetoplacental unit. We measured maternal and fetal plasma ANP concentrations in 19 parturients during elective caesarean section. Plasma ANP levels were also measured in seven nonpregnant women of the same age group. The baseline ANP concentration in parturients was significantly higher (29.77 +/- 6.06 pg/ml vs 7.37 +/- 2.1 pg/ml; mean +/- s.e.mean) than in their nonpregnant counterparts. The umbilical artery (UA) ANP concentration was significantly higher than the umbilical vein concentration (91.91 +/- 14.91 pg/ml vs. 40.04 +/- 9.71 pg/ml). Factors under the anaesthesiologist's control may influence maternal and fetal plasma ANP levels. There was a significant correlation between the volume of maternal Ringer's lactate infusion received and maternal ANP concentration. A significant correlation was seen between the total dose of ephedrine administered acutely prior to delivery and the UA ANP concentration. These data suggest that: 1) increased blood volume during pregnancy is associated with increased maternal plasma ANP levels, and 2) the fetus can produce its own ANP, and is thereby capable of responding to ANP stimulating factors.

Responsible alcohol service: a study of server, manager, and environmental impact

A responsible alcohol-service training program was evaluated for its impact on changing beliefs, knowledge, and behavior in 97 servers and 43 managers and on changing establishment policies that encourage safer drinking environments. The training program had a significant impact on changing the beliefs and knowledge of both servers and managers. Observation 4 to 6 weeks after training showed no effects on server behavior, but there was a tendency toward more establishment policies compared with controls.

In vivo canine coronary artery laser irradiation: photodynamic therapy using dihematoporphyrin ether and 632 nm laser. A safety and dose-response relationship study

This study examined the safety and dose-response relationships of 632-nm laser irradiation of photosensitized normal coronary arteries in 27 dogs. Fifteen received 2.5 mg/kg dihematoporphyrin ether (DHE), seven received no sensitizer, and five had coronary instrumentation but no laser (sham laser procedures) at nine coronary sites--four sensitized, five non-sensitized. Laser energy of 82 to 1,640 J/cm2 was delivered via a 584 microns diffusing-tip optical fiber, providing estimated tissue fluences of 20 to 410 J/cm2. Serial electrocardiograms and selective coronary arteriograms were performed up to 1 month post laser irradiation. Histologic examination was performed of all treated sites. Tissue fluences less than 200 J/cm2 produced no permanent electrocardiographic or angiographic changes; reversible spasm occurred in 2/8 photosensitized-lased, 0/2 non-photosensitized-lased. Minor medial damage occurred in 1/8 sensitized-lased, 1/2 non-sensitized-lased, and 0/9 sham-lased sites. At tissue fluences greater than 200 J/cm2 4/7 sensitized-lased animals died prematurely--one due to immediate and irreversible coronary spasm and Q wave infarction, one due to fibrillation during 48-hour follow-up coronary angiography (normal angiograms), two with normal electrocardiograms and angiograms within one day of undetermined death; 0/5 non-sensitized-lased animals expired or had coronary spasm; and 3/7 sensitized-lased and 0/5 non-sensitized/lased had significant medial to adventitial histologic damage. Coronary irradiation at less than 200 J/cm2 appears to be safe for photodynamic treatment of atherosclerotic lesions. Pretreatment for coronary spasm is appropriate.

A polygenic model for the evolution and maintenance of conditional strategies

We develop a genetic model for conditional strategies which places such strategies in the context of phenotypic plasticity. The model, which treats conditional strategies as polygenic threshold traits, indicates that, given requisite genetic variation in reaction norms, conditional strategies will evolve to their optimum level and be maintained by stabilizing selection, provided environmental variation results in a fitness trade-off for the alternative conditional phenotypes. The precise value for the evolutionary optimum is found to depend primarily on the probability density function of the environmental variation that influences the production of the conditional phenotypes and the magnitude of the fitness trade-offs of the conditional phenotypes across such environmental variation. The model is tested by application to three well-studied conditional strategies. In each case the predictions of the model are in good agreement with the results of these studies.

Protein kinase C activity and contractile responsiveness in senescent blood vessels

To examine Ca2(+)-signaling receptor function in the aging vasculature, the status of the diacylglycerol/protein kinase C (DAG/PKC) arm of the signal transduction pathway was assessed. contractile responsiveness to the PKC activator, phorbol 12-myristate 13-acetate (PMA), is substantially reduced in aortae from 24-month-old Fischer 344 rats compared to 6-month-old rats. PKC activity is reduced in all senescent vessels yet studied including aorta, renal artery, iliac artery and vena cava. This may account for the reduced contractile responsiveness. Additionally, PMA-stimulated PKC translocation is substantially reduced in senescent aorta and this may also contribute to reduced contraction.

Role of insulin-like growth factors and the type I insulin-like growth factor receptor in the estrogen-stimulated proliferation of human breast cancer cells

Estrogen sensitizes the MCF-7 estrogen-responsive breast cancer cell line to the mitogenic effect of insulin and the insulin-like growth factors (IGFs). This sensitization is specific for estrogen and occurs at physiological concentrations of estradiol. Dose-response experiments with insulin, IGF-I, and IGF-II suggested that the sensitization is mediated through the type I IGF receptor. Binding experiments with 125I-IGF-I and hybridization of a type I IGF receptor probe to RNA showed that the levels of the type I IGF receptor and its mRNA are increased 7- and 6.5-fold, respectively, by estradiol. IGF-I and estradiol had similar synergistic effects on other estrogen-responsive breast cancer cell lines, but IGF-I alone increased the proliferation of the MDA MB-231 cell line which is not responsive to estrogens. These experiments suggest that an important mechanism by which estrogens stimulate the proliferation of hormone-dependent breast cancer cells involves sensitization to the proliferative effects of IGFs and that this may involve regulation of the type I IGF receptor.

Lipocortin-1 immunoreactivity in the human pituitary gland

We evaluated the distribution of lipocortin-1 immunoreactivity in 118 immature or mature human hypophyses using the peroxidase-antiperoxidase (PAP) technique with a polyclonal rabbit antiserum against lipocortin-1. Serial sections were evaluated for five pituitary hormones and S-100 protein immunoreactivity to compare their distributions with that of lipocortin-1. Scattered or moderate numbers of cells exhibited lipocortin-1 immunoreactivity in the pars distalis of 89 subjects ranging in age from 27 weeks' gestation to 83 years. Seven immature and seven aged specimens exhibited no immunostaining, while 15 specimens from older individuals exhibited only rare immunostaining. Immunostaining did not appear to co-localize selectively with any specific pituitary hormone, although the distribution of immunoreactivity did overlap that of some corticotrophs and was seen in elongated processes of S-100-containing folliculostellate cells. Lipocortin-1 was also found in epithelial cells lining colloid cysts of the residual pars intermedia in 115 of 118 pituitaries ranging in age from 23 weeks' gestation to 83 years. In many intermediate lobe cysts, lipocortin-1 exhibited a pattern of immunoreactivity that partially overlapped the distribution of S-100 protein immunostaining, although the pattern was not identical. Pre-absorption of anti-lipocortin-1 antiserum with lipocortin-1-coupled Sepharose-4B immunoreactivity resulted in loss of immunoreactivity in both lobes. No lipocortin-1 immunoreactivity was seen in the neurohypophysis.

Chloroprocaine antagonism of epidural opioid analgesia: a receptor-specific phenomenon?

Sixty healthy patients scheduled for elective cesarean delivery under epidural anesthesia were randomized to receive either lidocaine or 2-chloroprocaine as the primary local anesthetic agent. When patients first complained of postoperative pain in the recovery room, they were given either fentanyl 50 micrograms or butorphanol 2 mg, epidurally, in a randomized, blinded fashion. Postoperative analgesia, quantitated on a visual analogue scale, as well as time elapsed until first request for supplemental opioid, did not differ for patients receiving butorphanol after either 2-chloroprocaine or lidocaine anesthesia. In contrast, epidural fentanyl produced a shorter and lesser degree of sensory analgesia after 2-chloroprocaine use, whereas epidural fentanyl after lidocaine anesthesia provided pain relief similar to that seen in the butorphanol groups. Side effects were limited to somnolence with butorphanol and pruritus with fentanyl. No evidence of respiratory depression was seen in any patient. We conclude that 2 mg of butorphanol epidurally provides approximately 2 to 3 h of effective analgesia after cesarean delivery with either lidocaine or 2-chloroprocaine anesthesia. Epidural fentanyl seems to be antagonized when 2-chloroprocaine, but not lidocaine, is used as the primary local anesthetic agent. We suggest a possible mu-receptor-specific etiology for this effect.

Fulminant monophasic multiple sclerosis, Marburg's type

The clinical, neuroradiological and necropsy findings are described in a 49 year old woman with long-standing idiopathic pulmonary haemosiderosis and acute monophasic multiple sclerosis (Marburg's type). Progression of the demyelinating process produced blindness and paraplegia over three weeks. At five weeks, magnetic reasonance imaging (MRI) studies showed lesions in the pons and left occipital lobe. The patient died 10 weeks after onset of symptoms. Necropsy examination revealed acute plaques in the optic chiasm, and the white matter around the lateral and fourth ventricle and spinal cord. Similarities between this and previously described cases of Marburg's disease are discussed.

Anabolic steroid use in adolescent athletes

Anabolic steroids are being used by adolescents largely to improve athletic performance but also to improve their appearance and to obtain peer approval. With the appropriate knowledge about the effects and side effects of anabolic steroids, primary care physicians can adequately educate teenagers, parents, teachers, and coaches about them and can screen for steroid use, if necessary.

Role of epinephrine in the development of hypertension in Dahl salt-sensitive rats

The present experiments were designed to test the hypothesis that adrenal epinephrine contributes to the development of hypertension in the Dahl salt-sensitive (DS) rat. All studies were carried out in conscious male DS and Dahl salt-resistant (DR) rats weighing 200-240 g. An indwelling femoral arterial catheter was placed for blood sampling and measurement of blood pressure. After 5 days of either a high salt (7% NaCI) or a normal salt (1% NaCl) dietary regimen, DS and DR rats were subjected to an acute stress paradigm (graded electrical footshock). There were no differences in basal plasma catecholamine concentrations or in the acute pressor responses to graded footshock between the four substrain/diet groups. However, in both DS and DR rats, plasma epinephrine responses to acute footshock were greater on a 7% than on a 1% NaCl diet. Additional groups of DS rats were treated with an inhibitor of adrenal phenylethanolamine N-methyltransferase, SK&F 29,661 (1-2 g/kg body wt/day) or with vehicle. Three days after placement of an arterial catheter, rats were placed on a 7% NaCl diet, and blood pressure was measured daily for an additional 3 weeks. Although SK&F 29,661 treatment was effective in reducing adrenal epinephrine content and apparent release by approximately 80%, treatment did not alter the time course of salt-induced changes in blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of naloxone on renin and pressor responses to acute renal hypotension in rats

Reduction of renal perfusion is followed by increases in plasma renin activity (PRA) and arterial pressure. The present experiments were designed to determine if an opiate antagonist would alter pressor or renin responses to acute reduction of renal arterial pressure (RAP) in anesthetized rats. Male Sprague-Dawley rats were anesthetized with Inactin, and an adjustable constrictor device was placed around the abdominal aorta proximal to the renal arteries. One-half of the animals were pretreated with the opiate antagonist naloxone (2 mg/kg iv), and the other one-half were pretreated with saline vehicle. The abdominal aorta was then constricted to reduce RAP by 25% (measured as femoral arterial pressure) in one-half of the animals in each pretreatment group. Compared with vehicle pretreatment, naloxone pretreatment did not alter the PRA response to aortic constriction; however, naloxone did attenuate the pressor response. We conclude that 1) the PRA response to acute reduction of renal arterial pressure is not dependent on an opiate mechanism in the rat, and 2) attenuation of the pressor response to aortic constriction by naloxone in intact rats is not secondary to a suppression of the PRA response.

Anaesthetic management of myocardial infarction in a parturient

Myocardial infarction is encountered rarely during pregnancy, but when it occurs the event is life-threatening to both mother and fetus. Data on maternal and fetal outcome are limited, but overall maternal mortality approaches 35%, and 40% of deaths occur during the third trimester. We present a case of myocardial infarction occurring at 38 weeks gestation, and discuss the anaesthetic management of the problems encountered during labour and delivery.

The prospective use of population pharmacokinetics in a computer-driven infusion system for alfentanil

Maitre et al. recently evaluated the accuracy of a set of previously determined population pharmacokinetic parameters for the opioid alfentanil using data from an earlier study in which the drug had been administered using a computer-controlled infusion pump (CCIP). The present study evaluated the accuracy of these same parameters in a CCIP prospectively in two groups of clinically dissimilar patients: 29 healthy female day surgery patients and 11 relatively older and less healthy male inpatients. In addition, another set of pharmacokinetic parameters, previously determined by Scott et al. in the CCIP in 11 male inpatients was also evaluated. The bias and inaccuracy were assessed by the median performance error (MDPE) and the median absolute performance error (MDAPE) in which the performance error was determined as the difference between measured and target serum concentration as a fraction of the target serum concentration. Unlike Maitre et al., the current study found a consistent bias in both populations. The MDPE was +53% and the MDAPE was 53%, with no difference between patient groups. In the 11 patients studied using the Scott et al. pharmacokinetic parameters, the MDPE was +1% and the MDAPE was 17%. The parameters of Scott et al. were further tested by simulating the serum concentrations that would have been achieved had they been used in the CCIP in the first 40 patients; results indicated MDPE of +2% and an MDAPE of 18%. Therefore, reasonably reliable and accurate target serum concentrations of alfentanil can be achieved using the pharmacokinetic parameters of Scott et al. in a CCIP.(ABSTRACT TRUNCATED AT 250 WORDS)

The cardiac, obstetric, and anesthetic management of pregnancy complicated by acute myocardial infarction

Myocardial infarction (MI) occurring during pregnancy is a rare but potentially lethal event for both mother and fetus, particularly when it occurs in the third trimester or peripartum period. The authors report two cases of MI occurring in the third trimester of pregnancy and review the literature. Management of the acute infarct and the medical, obstetric, and anesthetic considerations in such patients during labor and delivery are discussed. Successful use of percutaneous transluminal coronary angioplasty is described in a patient with evolving MI and ongoing pain. The preferred method of delivery in the pregnant MI patient is addressed, with emphasis on the need for individualization of care and coordination between the cardiac, obstetric, and anesthetic teams. Finally, the authors review the risks of subsequent pregnancy in this patient population.

Spinal opioids in the management of obstetric pain

Spinal opioids have become increasingly popular agents for providing analgesia during labor, augmenting anesthesia during cesarean section, and providing pain relief after operative delivery. The development of spinal opioids in the management of obstetric pain is reviewed.

Role of calcium in adrenergic neurochemical transmission in the aging heart

The effect of modification of extracellular Ca2+ concentration ([Ca2+]0), the administration of the neuronal Ca2+ channel blocker, omega-conotoxin, and the calcium (Ca2+) ionophore, ionomycin, were examined in the isolated heart of male Fisher-344 rats 6 and 24 months of age. Hearts with the right cardiac sympathetic nerve intact were isolated and perfused with Krebs-Ringer solution containing cocaine (10(-6) M) to block uptake 1, metanephrine (10(-6) M) to block uptake 2 and yohimbine (3 X 10(-6) M) to prevent alpha 2 receptor inhibition of Ca2+ influx. The nerve was stimulated with frequencies of 2, 6 and 12 Hz for 1 min and NE output was determined by high-performance liquid chromatography/electrochemical methods. Effluent of hearts from 6-month-old rats contained higher levels of NE than effluent of hearts from 24-month-old rats at all frequencies of stimulation when perfused with either normal (1.2 mM), low (0.3 mM) or high (4.8 mM) [Ca2+]0. Even when high [Ca2+]0 was used to make more Ca2+ available, the amount of NE in the effluent of 24-month-old animal hearts was only approximately 54% of that found in the effluent of 6-month-old animal hearts perfused with normal [Ca2+]0. omega-Conotoxin caused a greater decrease in NE release in the older preparations suggesting that the neuronal Ca2+ channels of older preparations are more susceptible to blockade than those of younger preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Bupivacaine with and without epinephrine for intercostal nerve block

In a double-blinded study, 15 American Society of Anesthesiologists class I or II patients, following lateral thoracotomy with general anesthesia, were randomized into two groups for intercostal nerve block with either bupivacaine, 0.5%, and epinephrine, 1:200,000, or plain bupivacaine, 0.5%. Blood concentrations of bupivacaine, epinephrine, and norepinephrine were serially measured. Blood pressure, heart rate, respiratory rate, temperature, and electrocardiogram were monitored. Peak blood bupivacaine concentrations were significantly lower in patients receiving bupivacaine with epinephrine. Peak epinephrine concentrations were significantly greater in patients receiving bupivacaine with epinephrine, but still within a safe range. No significant differences were seen in heart rate, blood pressure, respiratory rate, or temperature between the two groups, and/no dysrhythmias occurred. Peak norepinephrine concentrations were not significantly different between the two groups. The potential risk of toxic bupivacaine blood concentrations associated with intercostal nerve blocks can be reduced by the addition of epinephrine at a concentration of 1:200,000.

Reversal of bupivacaine epidural anesthesia by intermittent epidural injections of crystalloid solutions

This study was designed to determine whether epidural motor blockade could be reversed by postoperative injections of crystalloid solutions via the epidural catheter. Twenty-seven patients (ASA physical status I, nonlaboring) had epidural anesthesia with 0.75% bupivacaine for elective cesarean delivery. Postoperatively, patients were randomized to receive three 15-mL injections (over 30 min) of crystalloid solutions (normal saline or Ringer's lactate) or no treatment (control) via the epidural catheter. Degree of motor and sensory blockade was evaluated with an investigator blinded to treatment group. Rate of resolution of sensory blockade was not different among groups. However, time for resolution of motor blockade was more than twice as long in the control group than in either treatment group (control = 178 +/- 70 min vs Ringer's lactate = 84 +/- 44 min, normal saline = 70 +/- 38 min, P = 0.001). The data suggest that unwanted motor blockade due to epidural anesthesia can be reversed by epidural injections of crystalloid solutions.

Ontogeny of epidermal growth factor receptor and lipocortin-1 in fetal and neonatal human lungs

The ontogeny and distribution of the epidermal growth factor (EGF) receptor and lipocortin-1, a major cellular substrate of the EGF receptor, were evaluated in a developmental series of fetal and neonatal human lungs (8 to 41 weeks' gestation and stillborn to 16 days' postnatal age). The peroxidase anti-peroxidase technique with two polyclonal antibodies recognizing the EGF receptor and one polyclonal antibody recognizing lipocortin-1 were used for immunohistochemical localization. Extensive or scattered bronchiolar EGF receptor immunoreactivity appeared in the entire series of frozen lung specimens from 15 to 32 weeks' gestation. Bronchial glands exhibited EGF receptor immunostaining from 19 weeks onward, and immunoreactivity in bronchial epithelium was detected from 23 weeks onward. Most tracheas showed extensive lipocortin-1 immunoreactivity in the epithelium beginning at 10 weeks' gestation. Immunostaining was also seen in cells lining the ducts of submucosal glands after 15 weeks' gestation and in nonmucous acinar cells of tracheal glands after their appearance at 18 weeks' gestation. Bronchial epithelium exhibited lipocortin-1 immunoreactivity from 12 weeks' gestation onward. Bronchial gland necks became immunostained from 16 weeks' gestation onward, followed by acinar immunostaining as they subsequently developed. Bronchiolar epithelium was immunostained as early as 12 weeks, beginning with the largest airways, and by 24 weeks extending distally to the bronchioloalveolar portals. Lipocortin-1 immunostaining of larger conducting airway epithelium was primarily confined to ciliated cells. Neither EGF receptor nor lipocortin-1 immunoreactivity was detected in alveolar type I or type II cells, fibrocytes, chondrocytes, or smooth muscle cells at any gestational age. These developmental patterns suggest that the EGF receptor and lipocortin-1 may participate in normal growth factor-induced proliferation of the conducting airways and their glands in the human fetal lung and trachea.

Thermal laser probe angioplasty: influence of constant tip temperature, plaque composition, and probe/vessel diameter ratio

Thermal laser angioplasty uses constant laser power, producing widely variable tip temperatures in vivo. Results have been suboptimal. We studied the effect of 50-400 degrees C tip temperatures on depth of ablation at 192 sites on plaqued and normal human aorta in vitro, and the angiographic and histologic response in vivo of 300-400 degrees C at probe/vessel ratios of 0.5-1.0, in 40 normal canine femoral artery segments. In vitro, there was a direct relationship between tip temperature and depth of ablation, r = 0.71 (all segments), r = 0.74 for fibrous plaque, but a poor correlation in fatty plaque r = 0.35. In fibrous plaque, there was proportionately more ablation at tip temperatures greater than 300 degrees C, mean depth 0.62 mm, than at 150-300 degrees C, mean 0.37 mm, (P less than .001). Ablation was similar in plaqued and normal aorta. In vivo, 300 degrees C, 350 degrees C, and 400 degrees C produced similar effects. At probe/vessel ratios less than 0.8, only disruption of internal elastic lamina was observed. At ratios greater than or equal to 0.8, spasm occurred in 39% (7/18), transmural damage in 28% (5/18), and perforation in one of 18. Ablation is not selective for plaque and is highly variable in fatty plaque. Tip temperatures above 300 degrees C produce greater ablation than at lower temperatures. In clinical applications, probe/vessel rations less than or equal to 0.7 may be most appropriate, and it appears that thermal remodeling may contribute more to outcome than plaque ablation.

Alpha 1 adrenergic receptor function in senescent Fischer 344 rat aorta

There have been numerous conflicting reports concerning alpha 1 adrenergic receptor-mediated blood vessel contraction during aging and possible changes in alpha 1 receptor transduction mechanisms have not been investigated. These studies assess capacity of the aging vascular alpha 1 receptor to stimulate production of inositol phosphates, which are its intracellular second messengers, and to elicit a contractile response via this pathway. Aortic ring segments from mature adult (6 month old) and senescent (24 month old) Fischer 344 rats were incubated with [3H]myo-inositol and then stimulated with the alpha 1 agonist norepinephrine (NE, 10(-7)M-3 x 10(-5)M) in the presence of LiCl (10mM), an inhibitor of inositol phosphate metabolism. There was a substantial increase in inositol phosphate accumulation throughout the dose range in aortic rings from 24 month old rats compared to 6 month old rats. This is an alpha 1 receptor response since it is blocked by the alpha 1 antagonist prazosin but not by the alpha 2 antagonist yohimbine. Aortic inositol phosphate accumulation in response to serotonin did not change with age. To assess second messenger stimulated contraction, aortic ring segments were placed in Ca++ free buffer and then stimulated with NE. Under these conditions Ca++ influx is eliminated and contraction depends on the actions of intracellular second messengers. There is an age-related reduction in aortic contraction in Ca++ free buffer. These results suggest that aortic alpha 1 receptor-mediated formation of inositol phosphate intracellular second messengers is enhanced during aging. Despite this, the capacity of senescent arteries to elicit contraction utilizing second messenger pathways seems to be deficient.