Munetaka Hirose

The antiproliferative effect of lidocaine on human tongue cancer cells with inhibition of the activity of epidermal growth factor receptor.

Local anesthetics suppress proliferation in several cancer cells. The mechanism of the suppression, however, is unknown. Our previous study shows that lidocaine, at the level of tissue concentration under topical or local administration, has a direct inhibitory effect on the activity of epidermal growth factor receptor (EGFR), which is a potential target for antiproliferation in cancer cells. Therefore, we hypothesized that lidocaine would suppress the proliferation of cancer cells through the inhibition of EGFR activity. We investigated the effects of lidocaine (40–4000 &mgr;M) on proliferation of a human tongue cancer cell line, CAL27, which has a high level of EGFR expression, and also examined the effect of lidocaine on epidermal growth factor (EGF)-stimulated autophosphorylation of EGFR in CAL27 cells. A clinical concentration of lidocaine (400 &mgr;M) suppressed both serum-induced and EGF-induced proliferation of CAL27 cells and inhibited EGF-stimulated tyrosine kinase activity of EGFR without cytotoxicity. A larger concentration of lidocaine (4000 &mgr;M) showed cytotoxicity with an antiproliferative effect. We suggest that the inhibition of EGF-stimulated EGFR activity is one of the mechanisms of the antiproliferative effect of lidocaine on CAL27 cells. Lidocaine administered topically within the oral cavity for cancer pain relief may suppress the proliferation of human tongue cancer cells.

The effect of postoperative analgesia with continuous epidural bupivacaine after cesarean section on the amount of breast feeding and infant weight gain

The purpose of this study is to determine the effect of postoperative analgesia on the amount of breast feeding and infant weight gain.Thirty parturients undergoing elective cesarean section under spinal anesthesia were randomly allocated to receive postoperative pain management with (S-E group, n = 15) or without epidural bupivacaine (S group, n = 15). Epidural analgesia was performed for 3 days with a continuous epidural infusion (0.7 mL/h) of 0.25% bupivacaine. Diclofenac was available on demand in all patients. The weight of milk fed by breast and the infant weight were measured for 11 days after cesarean section. In the S-E group, the visual analog pain score after surgery was significantly lower and both the weight of milk fed by breast and the infant weight during the study were significantly more than the respective values in the S group. The S group required a larger dose of diclofenac after the operation than did the S-E group. We suggest that satisfactory postoperative pain relief with continuous epidural bupivacaine for 3 days after cesarean section improved the amount of breast feeding and the gain of infant weight. (Anesth Analg 1996;82:1166-9)

Local anesthetics suppress nerve growth factor-mediated neurite outgrowth by inhibition of tyrosine kinase activity of TrkA

Local anesthetics (LAs) suppress sympathetic sprouting, which correlates with neuropathic pain. However, the precise mechanism of the suppression is unknown. Nerve growth factor (NGF) contributes to the sympathetic sprouting, and NGF signaling starts with NGF-stimulated autophosphorylation of TrkA, which is a high affinity receptor of NGF. We examined the effects of lidocaine, bupivacaine, and procaine on NGF signaling under suppression of NGF-stimulated neurite outgrowth in PC12 cells, which is a cellular model of sympathetic sprouting. To investigate the effect of these LAs on NGF-mediated neurite outgrowth of PC12 cells, cells were incubated with 40, 400, and 4000 &mgr;M of each LA. The effect of LAs on NGF-stimulated TrkA activity was examined to analyze autophosphorylation of TrkA using immunoprecipitation and immunoblotting. Cytotoxic effects of LAs on PC12 cells were also assessed by lactate dehydrogenase release and by propidium iodide staining. Lidocaine (400 &mgr;M), bupivacaine (40 and 400 &mgr;M), or procaine (4000 &mgr;M) suppressed either neurite outgrowth or autophosphorylation significantly without cytotoxicity. The inhibition of NGF-stimulated tyrosine kinase activity of TrkA might be involved in the mechanisms of suppression of neurite outgrowth induced by LAs.

Lidocaine Inhibits Tyrosine Kinase Activity of the Epidermal Growth Factor Receptor and Suppresses Proliferation of Corneal Epithelial Cells

Background: Although lidocaine is recognized as an excellent topical corneal analgesic, its toxic effect on corneal epithelial cells limits its use during corneal epithelial wound healing. Mechanism of the impairment of corneal reepithelialization with lidocaine, however, has not been evaluated. The authors’ previous study revealed that lidocaine inhibits the activity of tyrosine kinase receptors through the interaction with specific amino acid sequences around autophosphorylation sites, including acidic, basic, and aromatic amino acids. Epidermal growth factor receptor (EGFR), a tyrosine kinase receptor with an important role in epithelial cell proliferation after corneal wounding, also possesses these amino acids sequences around autophosphorylation sites. The authors hypothesized that lidocaine would suppress tyrosine kinase activity of EGFR and would impair corneal epithelial cell proliferation. Methods: To investigate the effect of lidocaine (4 μM–40 mM) on epidermal growth factor (EGF)–stimulated autophosphorylation of EGFR, the authors studied purified EGFR in microtubes. They cultured human corneal epithelial cells (HCECs) with EGF and lidocaine to investigate the effect of lidocaine on cell proliferation and on autophosphorylation of EGFR in HCECs. Results: Lidocaine (≥ 400 μM) significantly suppressed EGF-stimulated autophosphorylation of the purified EGFR. In the HCEC study, EGF alone stimulated cell proliferation and increased autophosphorylation of EGFR in HCECs. Lidocaine (≥ 400 μM) significantly suppressed both the proliferation of HCECs promoted by EGF and EGF-stimulated autophosphorylation of EGFR. Conclusion: Lidocaine directly inhibits tyrosine kinase activity of EGFR and suppresses the corneal epithelial cell proliferation.

Heart rate variability during chemical thoracic sympathectomy.

Background Chemical thoracic sympathectomy (CTS) resulted in profound bradycardia in a patient with severe posttherapeutic neuralgia. To clarify the cause of this bradycardia, the authors evaluated heart rate variability using a Poincare plot, which is a scatter diagram of the current R-R interval plotted against the R-R interval immediately preceding it, in this patient and in others scheduled for CTS or mandibular block (MB). Methods Twenty-three patients were scheduled for CTS (n = 13, CTS group) and for MB (n = 10, MB group). Heart rate and the SD of the R-R interval variabilities spreading along the x axis (SDRR) and perpendicularly along the diagonal line of the Poincare plot (SD sub [partial differential] RR) were evaluated before, just after, and 1 h after the block. Results Neither group had significant changes in heart rate. The MB group showed no significant change in the SDRR:SD sub [partial differential] RR ratio. In the CTS group, however, the SDRR:SD sub [partial diffenrential] RR ratio decreased significantly from 1.72 +/- 0.20 to 1.23 +/- 0.11 just after CTS. The previous patient, who had a high SDRR:SD sub [partial diffenrential] RR ratio of 3.45 before CTS, exhibited severe bradycardia (22 beats/min). Conclusions The SDRR:SD sub [partial diffenrential] RR ratio decreased after CTS without any significant concomitant change in heart rate. The decrease in the SDRR:SD sub [partial diffenrential] RR ratio indicates a reduction of cardiac sympathetic activity. However, CTS in patients having high SDRR:SD sub [partial diffenrential] RR ratios can result in profound bradycardia.

The effect of the partial pressure of oxygen on blood glucose concentration examined using glucose oxidase with ferricyan ion.

Glucose oxidase with ferricyan ion (GOD-F) is widely applied in clinical settings as a glucose sensor. However, blood oxygen concentration affects this blood glucose value because oxygen, at increased concentrations, consumes blood glucose, which cannot then be measured by this sensor. We investigated the effect of Po2 on blood glucose concentration in 48 patients who were breathing high concentrations of oxygen. Arterial and pulmonary arterial blood glucose values were analyzed using the GOD-F method and, as a control, the hexokinase method. The respective Po2 values were also measured. The blood glucose concentrations measured by the GOD-F method show a significant linear relation with that measured by the hexokinase method in both arterial (y = −24.4 + 1.01x, r = 0.99) and pulmonary arterial blood (y = −3.4 + l.01x, r = 0.96). The difference of intercepts is statistically significant, but because of the relatively large limits of agreement indicating any hidden extraneous variabilities, the error of the GOD-F method could not be assessed just by the difference. The equation defining the effect of Po2 on the percent change between blood glucose measured by the GOD-F method and that measured by the hexokinase method is −19.8/(1 + 203900/Po2268) (r = 0.62). This formula generally follows our measured materials and introduces the relationship among blood glucose value, Po2, and the error of the GOD-F method. We hesitate to suggest that the arterial blood glucose concentration when measured by the GOD-F method could be underestimated by as much as 20% in patients with high arterial oxygen pressure. The underestimation is not a clinical problem when blood glucose is high, but anesthesiologists should pay attention to easy evaluation of hypoglycemia by the GOD-F method when blood Po2 is high.

Premedication with Famotidine Augments Core Hypothermia during General Anesthesia

Background Animal studies have provided considerable evidence to support a role of histamine in the central nervous system in thermoregulation, and premedication with a histamine Hydrogen2 receptor antagonist before general anesthesia is used to reduce the risk of acid aspiration. The authors investigated whether premedication with famotidine had an effect on thermoregulation during general anesthesia.

Effect of the head-down tilt position during lower abdominal surgery on endocrine and renal function response

A head-down tilt position in awake subjects induces natriuresis, accompanied by reduced plasma levels of catecholamines, renin, angiotensin II, aldosterone, and antidiuretic hormone. We hypothesized that the head-down tilt position would counteract the surgical stress response which induces sodium and water retention and increases plasma levels of these hormones. We studied endocrine and renal function responses in patients during lower abdominal surgery, performed under sevoflurane anesthesia, at a 6° head-down tilt position (n = 10) versus a horizontal position (n = 10). The mean arterial pressure was maintained constant by adjusting the inspired concentration of sevoflurane. Heart rate, and the dose of sevoflurane, decreased significantly in the head-down tilt position. Increases in plasma norepinephrine and epinephrine levels during surgery were significantly less in the head-down tilt position; in contrast, plasma aldosterone and cortisol levels were increased significantly in this position compared to the horizontal position. Both fractional and total urinary excretion of sodium increased significantly in the head-down tilt position compared to the horizontal position. Plasma renin activity, and antidiuretic hormone and atrial natriuretic peptide levels, as well as urine volume, creatinine clearance, and water clearance showed no positional variation. We conclude that the 6° head-down tilt position reduces increased sympathetic activity and lessens renal tubular sodium reabsorption during lower abdominal surgery under sevoflurane anesthesia. Other stress hormones, however, increase more in the head-down tilt position than in the horizontal position.

Mechanism Underlying the Changes in Plasma Potassium Concentration during Infusion of Isosmotic Nonelectrolyte Solution

Generally, during infusion of an isosmotic nonelectrolyte solution that permeates the cell membrane, plasma K+ concentration ([K+]pl) either does not change or it increases slightly. The mechanism underlying this [K+]pl change has not been clarified. We continuously monitored the [K+]pl and plasma Na+ concentration ([Na+]pl) for 10 min during isosmotic mannitol infusion of 1.6 ml/100 g body weight in rats with intact kidney function (intact mannitol group). In addition, in nephrectomized rats, we compared the [K+]pl change during infusion with isosmotic mannitol (which permeates the cell membrane; mannitol nephrectomized group) with that during infusion with isosmotic sucrose (which does not permeate the cell membrane; sucrose nephrectomized group) to evaluate the effect of cell volume regulation. In the intact mannitol group, [Na+]pl decreased with dilution, and [K+]pl remained relatively constant. In the sucrose nephrectomized group, [K+]pl decreased by the same percentage as [Na+]pl and gradually increased to greater than the control level. In the mannitol nephrectomized group, however, [K+]pl increased immediately after the beginning of the infusion and reached the same level as that in the sucrose nephrectomized group. To confirm that the difference in [K+]pl between the mannitol and sucrose nephrectomized groups was dependent on cell volume regulation, we investigated the changes in mean corpuscular volume of red blood cells, using a Coulter counter. This value remained constant during isosmotic sucrose infusion but increased during isosmotic mannitol infusion, returning to the original volume after the infusion. We kept [HCO3-] and pH constant throughout the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthetic pentapeptides inhibiting autophosphorylation of insulin receptor in a non‐ATP‐competitive mechanism

In an attempt to develop non‐ATP‐competitive inhibitors of the autophosphorylation of IR, the effects of the synthetic peptides, Ac‐DIY1158ET‐NH2 and Ac‐DY1162Y1163RK‐NH2, on the phosphorylation of IR were studied in vitro. The peptides were derived from the amino‐acid sequence in the activation loop of IR. They inhibited the autophosphorylation of IR to 20.5 and 40.7%, respectively, at 4000 µM. The Asp/Asn‐ and Glu/Gln‐substituted peptides, Ac‐NIYQT‐NH2 and Ac‐NYYRK‐NH2, more potently inhibited the autophosphorylation than did the corresponding parent peptides. The inhibitory potencies of the substituted peptides were decreased with increasing concentrations of ATP, indicating that these peptides employ an ATP‐competitive mechanism in inhibiting the autophosphorylation of IR. In contrast, those of the parent peptides were not affected. Mass spectrometry showed that the parent peptides were phosphorylated by IR, suggesting that they interact with the catalytic loop. Moreover, docking simulations predicted that the substituted peptides would interact with the ATP‐binding region of IR, whereas their parent peptides would interact with the catalytic loop of IR. Thus, Ac‐DIYET‐NH2 and Ac‐DYYRK‐NH2 are expected to be non‐ATP‐competitive inhibitors. These peptides could contribute to the development of a drug employing a novel mechanism. Copyright