Insulin receptor isoform A, a newly recognized, high-affinity insulin-like growth factor II receptor in fetal and cancer cells.

Insulin-like growth factor II (IGF-II) is a peptide growth factor that is homologous to both insulin-like growth factor I (IGF-I) and insulin and plays an important role in embryonic development and carcinogenesis. IGF-II is believed to mediate its cellular signaling via the transmembrane tyrosine kinase type 1 insulin-like growth factor receptor (IGF-I-R), which is also the receptor for IGF-I. Earlier studies with both cultured cells and transgenic mice, however, have suggested that in the embryo the insulin receptor (IR) may also be a receptor for IGF-II. In most cells and tissues, IR binds IGF-II with relatively low affinity. The IR is expressed in two isoforms (IR-A and IR-B) differing by 12 amino acids due to the alternative splicing of exon 11. In the present study we found that IR-A but not IR-B bound IGF-II with an affinity close to that of insulin. Moreover, IGF-II bound to IR-A with an affinity equal to that of IGF-II binding to the IGF-I-R. Activation of IR-A by insulin led primarily to metabolic effects, whereas activation of IR-A by IGF-II led primarily to mitogenic effects. These differences in the biological effects of IR-A when activated by either IGF-II or insulin were associated with differential recruitment and activation of intracellular substrates. IR-A was preferentially expressed in fetal cells such as fetal fibroblasts, muscle, liver and kidney and had a relatively increased proportion of isoform A. IR-A expression was also increased in several tumors including those of the breast and colon. These data indicate, therefore, that there are two receptors for IGF-II, both IGF-I-R and IR-A. Further, they suggest that interaction of IGF-II with IR-A may play a role both in fetal growth and cancer biology.

Insulin receptor activation by IGF-II in breast cancers: evidence for a new autocrine/paracrine mechanism.

IGF-II, produced by breast cancer epithelial and stromal cells, enhances tumor growth by activating the IGF-I receptor (IGF-I-R) via autocrine and paracrine mechanisms. Previously we found that the insulin receptor (IR), which is related to the IGF-I-R, is overexpressed in breast cancer cells. Herein, we find that, in breast cancer the IR is activated by IGF-II. In eight human breast cancer cell lines studied there was high affinity IGF-II binding to the IR, with subsequent IR activation. In these lines, IGF-II had a potency up to 63% that of insulin. In contrast, in non malignant human breast cells, IGF-II was less than 1% potent as insulin. Via activation of the IR tyrosine kinase IGF-II stimulated breast cancer cell growth. Moreover, IGF-II also activated the IR in breast cancer tissue specimens; IGF-II was 10-100% as potent as insulin. The IR occurs in two isoforms generated by alternative splicing of exon 11; these isoforms are IR-A (Ex11-) and IR-B (Ex11+). IR-A was predominantly expressed in breast cancer cells and specimens and the potency of IGF-II was correlated to the expression of this isoform (P<0.0001). These data indicate, therefore, that the IR-A, which binds IGF-II with high affinity, is predominantly expressed in breast cancer cells and represents a new autocrine/paracrine loop involved in tumor biology.

Overexpression of membrane glycoprotein PC-1 in MDA-MB231 breast cancer cells is associated with inhibition of insulin receptor tyrosine kinase activity.

MDA-MB231 human breast cancer cells are unresponsive to insulin and contain a glycoprotein inhibitor of insulin-stimulated insulin receptor (IR) tyrosine kinase activity. Prior studies in both fibroblasts from insulin- resistant non-insulin-dependent diabetes mellitus patients and transfected cells indicate that overexpression of membrane glycoprotein PC-1 reduces IR tyrosine kinase activity. In the present study, we measured PC-1 content and activity in MDA-MB231 and four other human breast cancer cell lines. We observed that PC-1 expression was 3- to 30-fold higher in MDA-MB231 cells when compared with the other breast cell lines. Wheat germ agglutinin extracts of MDA-MB231 cells inhibited IR tyrosine kinase activity. Treatment of these extracts with an antibody to PC-1 significantly reduced their ability to inhibit insulin-stimulated IR tyrosine kinase activity. In addition, when cell clones with different PC-1 activity were selected from MDA-MB231 cells, we found an inverse correlation (r = -0.741, P = 0.006) between the PC-1 activity and the insulin-stimulated IR autophosphorylation. A similar inverse correlation was observed in cell clones derived from the insulin-responsive breast cancer cell line MCF-7. By both immunoprecipitation and cross-linking studies we found PC-1 to be associated with IR. These studies indicate, therefore, that overexpression of PC-1 in MDA-MB231 cells may account, at least in part, for the reduced IR tyrosine kinase activity and suggest that PC-1 is a specific modulator of the IR activity in breast cancer cells.

Interleukin-1 blocks insulin and insulin-like growth factor-stimulated growth in MCF-7 human breast cancer cells by inhibiting receptor tyrosine kinase activity.

Interleukins-1 (IL-1s) are known to inhibit the growth of cultured breast cancer cells. We examined the effects of IL-1 alpha and IL-1 beta on insulin and insulin-like growth factor I (IGF-I) stimulation of cell growth and found that both IL-1s inhibited anchorage-dependent and independent growth of MCF-7 breast cancer cells. In cells incubated with IL-1 beta (100 U/ml), insulin receptor (IR) protein and messenger RNA were increased by 100%, while IGF-I receptor protein and transcript were not significantly changed. These data were confirmed by binding studies. Incubation of MCF-7 cells with IL-1s led, however, to a significant inhibition of IR and IGF-I receptor autophosphorylation (-55%) and phosphotransferase activity (-65%). Also, in 3T3/ HIR rat fibroblasts, transfected with and overexpressing IR, IL-1s decreased insulin-stimulated cell growth in soft agar and IR tyrosine kinase activity. The present findings suggest that IL-1s antagonize the insulin and IGF-I mitogenic effects in MCF-7 cells by blocking the receptor tyrosine kinase activity that is crucial for the mitogenic effect of these factors.

The hemodynamic and fibrinolytic response to low dose epinephrine and phenylephrine infusions during total hip replacement under epidural anesthesia.

Lower rates of deep vein thrombosis have been noted following total hip replacement under epidural anesthesia in patients receiving exogenous epinephrine throughout surgery. To determine whether this is due to enhanced fibrinolysis or to circulatory effects of epinephrine, 30 patients scheduled for primary total hip replacement under epidural anesthesia were randomly assigned to receive intravenous infusions of either low dose epinephrine or phenylephrine intraoperatively. All patients received lumbar epidural anesthesia with induced hypotension and were monitored with radial artery and pulmonary artery catheters. Patients receiving low dose epinephrine infusion had maintenance of heart rate and cardiac index whereas both heart rate and cardiac index declined significantly throughout surgery in patients receiving phenylephrine (p = 0.0001 and p = 0.0001, respectively). Tissue plasminogen activator (t-PA) activity increased significantly during surgery (p < 0.005) and declined below baseline postoperatively (p < 0.005) in both groups. Low dose epinephrine was not associated with any additional augmentation of fibrinolytic activity perioperatively. There were no significant differences in changes in D-Dimer, t-PA antigen, alpha 2-plasmin inhibitor-plasmin complexes or thrombin-antithrombin III complexes perioperatively between groups receiving low dose epinephrine or phenylephrine. The reduction in deep vein thrombosis rate with low dose epinephrine is more likely mediated by a circulatory mechanism than by augmentation of fibrinolysis.

A quantitative reverse transcription and polymerase chain reaction assay for human IGF-II allows direct comparison of IGF-II mRNA levels in cancerous breast, bladder, and prostate tissues.

Previously, we showed by in situ hybridization that insulin-like growth factor (IGF)-II is upregulated in approximately 50% of prostate, breast, and bladder tumours. In this study, a quantitative competitive reverse transcription and polymerase chain reaction (QC RT-PCR) assay was established and used to quantify human IGF-II mRNA levels in cells and tissues. In this QC RT-PCR assay, a competitor IGF-II RNA, prepared from a newly constructed plasmid encoding the human IGF-II sequence with a 110-bp fragment inserted, was added to RNA samples prior to RT-PCR. The human IGF-II specific QC RT-PCR assay has allowed us to readily compare the levels of IGF-II mRNA in human tissues and cultured cells. Consistent with our previous observations by in situ hybridization, IGF-II mRNA was up-regulated in 50% of cancerous breast tissues examined as compared to the matching benign tissues, and IGF-II mRNA levels were higher in bladder tumours than breast and prostate tumours. In summary, we present here quantitative data confirming that a subclass of breast cancer samples has elevated levels of IGF-II transcripts by the new competitive RT-PCR assay.

Complications after total hip replacement. The contralateral limb.

Six patients who had a total hip replacement, as well as a trochanteric osteotomy, while they were in the lateral decubitus position had complications involving the contralateral side. The complications included transient paresthesias, massive swelling of the thigh with myonecrosis, acute renal failure secondary to myoglobinuria, and arterial insufficiency that resulted in a below-the-knee amputation. In order to elucidate the causes of the complications, the external pressure of the contralateral femoral triangle and the blood flow to the contralateral foot were monitored intraoperatively in seventeen patients. The results supported the postulate that pressure at the groin is increased intraoperatively and that this can cause vascular compromise. Other proposed causes of the complications were pre-existing vascular disease, obesity, the lateral decubitus position of the patient on the operating table, and the use of hypotensive anesthesia. We found several techniques that may minimize complications in the contralateral limb during operations on the hip.

The effect of intravenous fixed-dose heparin during total hip arthroplasty on the incidence of deep-vein thrombosis. A randomized, double-blind trial in patients operated on with epidural anesthesia and controlled hypotension.

Heparin was given in fixed doses intravenously during unilateral primary total hip-replacement operations in a prospective, double-blind trial to assess the effect on the incidence of deep-vein thrombosis. One hundred and fifty patients were randomly assigned to one of two groups before the operation. Twenty-four patients were excluded from the study, leaving 126 patients. Group I consisted of sixty-six patients who received saline solution intravenously, and Group II comprised sixty patients who received heparin. All patients had epidural anesthesia with controlled hypotension. Fixed doses of heparin were administered five minutes before the operative incision was made and every thirty minutes throughout the operation. Mean arterial pressures were maintained at between fifty and sixty millimeters of mercury in all patients. Ascending venography was done on the seventh day after the operation. The incidence of deep-vein thrombosis was 24 per cent (sixteen of sixty-six patients) in Group I and 8 per cent (five of sixty patients) in Group II; the difference is significant (p = 0.03). The intraoperative loss of blood averaged 220 +/- 79 milliliters in Group I compared with 269 +/- 109 milliliters in Group II. An average of less than one unit of blood was transfused for each patient in each group. Postoperatively, there was no difference between the groups with regard to the amount of drainage that was collected in a Hemovac device or the values for hematocrit.

Intravenous versus oral initial load of propafenone for conversion of recent-onset atrial fibrillation in the emergency room: a randomized trial.

BACKGROUND: Non-valvular paroxysmal atrial fibrillation is a common clinical condition associated with a high risk of thromboembolism and hemodynamic problems which increase with the duration of arrhythmia. Therefore, even if arrhythmia ceases spontaneously within 24 hours in about half of the patients, a higher early conversion rate is desirable. Propafenone either by intravenous or oral load has been shown effective in conversion to sinus rhythm. METHODS: We consecutively randomized all emergency patients with non-valvular atrial fibrillation lasting no more than 48 hours to either intravenous or oral initial load of propafenone. They all received further oral doses if still on atrial fibrillation after the initial load. Exclusion criteria were: mean ventricular rate < 65 b/min, age > 75 years, recent acute myocardial infarction, overt heart failure, conduction defects, ventricular preexcitation, thyroid dysfunction, renal or hepatic insufficiency, pregnancy, current treatment with propafenone or other antiarrhythmic drugs, and intolerance to propafenone. Primary and secondary end-points were the conversion to sinus rhythm within 12 and 48 hours of randomization respectively. RESULTS: Ninety-seven patients were randomized to intravenous (n = 49) or oral (n = 48) treatment. Overall, sinus rhythm restoration occurred in 83.3% of patients within 12 hours and in 98.9% at 24 hours. Recovery rate resulted significantly greater for intravenous treatment at 1 and 3 hours (p < 0.001 and p = 0.001, respectively). At 6, 12 and 24 hours no significant difference between the two groups was observed (p = 0.77, p = 0.81 and p = 0.99, respectively). No patient needed treatment suspension. CONCLUSIONS: In patients with recent-onset non-valvular atrial fibrillation treated with propafenone within 48 hours, conversion to sinus rhythm occurred in more than 80% within 12 hours. Even if intravenous initial load appears to be slightly more rapid, the oral way is easier to administer and cheaper. The choice may depend on the specific organization of the single emergency room.

[Detection by the immunoenzymatic test ELISA of IgM anti-Cysticercus cellulosae antibodies in the cerebrospinal fluid in neurocysticercosis]. / Detecção pelo teste imunoenzimático ELISA de anticorpos IgM anti-Cysticercus cellulosae no líquido cefalorraqueano na neurocisticerose.

IgM antibodies against Cysticercus cellulosae in the cerebrospinal fluid (CSF) was demonstrated by ELISA immunoenzymatic assay in neurocysticercosis. CSF samples of 41 patients were analyzed for this purpose. Diagnosis was neurocysticercosis in 26 and neurosyphilis in 5; abnormalities were not registered in the other 10 cases. Neurosyphilis samples and no-abnormalities samples were considered as control groups. ELISA IgM assay for cysticercosis was negative in all CSF samples of control groups and it was positive in 12 of the 26 CSF samples of the neurocysticercosis group (46.2%). Titers ranged from 4 till 32. Positive results were no more obtained after previous treatment of CSF samples by 2-mercaptoethanol. ELISA IgM and IgG titers were compared. IgM titers wee higher than IgG titers in two cases. Results obtained were compared to those found through complement fixation, immunofluorescence and hemagglutination tests for the diagnosis of neurocysticercosis.

[Synchronous carcinoma of the colorectum]. / Il carcinoma sincrono del colon-retto.

The incidence of synchronous carcinoma of the large intestine is rising in relation to a greater oncogenic environmental charge and increased average life expectancy. There is also a constant risk of not recognising the disease, especially in the case of small carcinoma and, to a greater extent, in patients operated during the occlusive phase. Having underlined the diagnostic value of a correct preparation of the colon prior to instrumental tests, the authors emphasise the importance of a careful intraoperative exploration of the viscera, its preliminary confinement in occluded subjects and repeated surgery in the event of doubts regarding the monolocation of the tumour. Lastly, they underline the importance of postoperative radiological and endoscopic controls since these tests mark both the successful outcome of treatment and the start of follow-up.

Venous levels of lidocaine and bupivacaine after midtarsal ankle block.

BACKGROUND: No data are available on blood levels of local anesthetics after ankle block. METHODS: Eighteen patients received 13 ml 2% lidocaine and ten received 30 ml 0.75% bupivacaine for unilateral or bilateral midtarsal ankle blocks, respectively. Blood levels were drawn at 15, 30, 45, 60, 90, 120, and 180 minutes after injections. All patients had forefoot surgery with elastic bandages (Esmarch) applied as a tourniquet immediately above the ankle intraoperatively. RESULTS: The mean peak level of lidocaine was 1.1 micrograms/ml, and of bupivacaine, 0.5 micrograms/ml. The mean duration of analgesia was 17 hours with 0.75% bupivacaine. Duration could not be assessed in the lidocaine group because these were ambulatory patients. CONCLUSION: The low peak level of local anesthesia and the prolonged analgesia confirmed the safety and efficacy of midtarsal ankle block for forefoot surgery and suggest that bupivacaine may be the local anesthetic agent of choice.

Management of the recovering alcoholic who seeks cosmetic surgery.

Plastic surgeons are likely to see patients who have successfully completed alcohol or drug abusers' rehabilitation programs. These patients are seeking to improve their appearance and, hence, their self-image. Unless special care is given to the recovering alcoholic, he or she is at risk of readdiction to alcohol or to drugs after surgery. Recommendations are made regarding the timing of elective operations, the use of drugs during and after the procedure, and reliance on a dependable third party to dispense drugs postoperatively.

Pulse oximeter waveforms from the finger and toe during lumbar epidural anesthesia.

BACKGROUND AND OBJECTIVES: To determine whether lumbar epidural anesthesia affects pulse oximeter signals in the upper or lower extremity, 13 ASA I patients were studied. METHODS: Temperature and pulse oximeter probes were placed on the finger and the toe. RESULTS: After epidural injection, the amplitude of the pulse oximeter waveform on the toe increased eight-fold but declined by 50% in the finger. The increase in amplitude of the pulse oximeter waveform in the foot preceded the temperature rise. CONCLUSIONS: More reliable pulse oximeter signals may be obtained from the toe than the finger during lumbar epidural anesthesia. Furthermore, the increase in the pulse amplitude from the toe may aid in the early detection of successful epidural block.

Extradural anaesthesia in patients with previous lumbar spine surgery.

We studied prospectively 1381 patients undergoing extradural anaesthesia for total hip or total knee replacement, to determine if extradural anaesthesia can be performed reliably in patients who have had previous lumbar spine surgery. Fifty-two of the 57 patients (91.2%) who had undergone lumbar spine surgery received a successful extradural anaesthetic, and 1307 of 1324 patients without previous back surgery had successful extradural anaesthesia (98.7% success) (P less than 0.0001). No late complications were observed. Causes for failure of extradural anaesthesia in patients who had previously undergone lumbar spine surgery included technical difficulty (three) and inadequate spread (two).

A simple preoperative method of screening for alcoholism.

The patient with an alcohol problem represents a higher risk to the aesthetic surgeon. Problems may develop intraoperatively, or in the immediate postoperative period due to lack of compliance, ultimately a higher risk of patient dissatisfaction. Identification of this group of patients is helpful preoperatively. We propose a screening method consisting of two well-conceived questions and confirmation by appropriate laboratory data.

Hemodynamic response to low-dose epinephrine infusion during hypotensive epidural anesthesia for total hip replacement.

The hemodynamic response to reduction in blood pressure after epidural anesthesia in elderly patients is poorly defined. Therefore, hemodynamic measurements using radial artery and thermodilution pulmonary artery catheters were performed in 85 patients undergoing total hip replacement in whom blood pressure was allowed to decrease in order to minimize blood loss. Measurements were made in the lateral position prior to and after induction of epidural anesthesia to T4 or above when mean arterial pressure (MAP) had fallen to 50-55 mmHg. Four non-randomized groups of patients were identified: those requiring zero, less than 1 microgram/minute, 1-2 micrograms/minute or 2-5 micrograms/minute, respectively, of intravenous epinephrine to maintain MAP at 50-55 mmHg. In patients receiving no epinephrine, MAP, heart rate (HR), stroke volume (SV), cardiac index (CI), pulmonary artery diastolic pressure (PAD), left ventricular stroke work index (LVSWI) and systemic vascular resistance (SVR) fell significantly from baseline. Low-dose epinephrine infusions modified this response by increasing SV and CI and reducing SVR, but had little consistent effect on PAD, HR and LVSWI. Increases in SV and CI were significantly related to the dose of epinephrine administered. Low-dose intravenous epinephrine infusions preserve cardiac output during hypotensive epidural anesthesia in elderly patients.

Haemodynamic effects and outcome analysis of hypotensive extradural anaesthesia in controlled hypertensive patients undergoing total hip arthroplasty.

We have examined the safety of induced hypotension produced by extradural anaesthesia in patients with medically controlled hypertension. The haemodynamic response to induced hypotension was assessed in 38 non-hypertensive and 31 controlled hypertensive patients. All received extradural anaesthesia to T4 or above which decreased mean arterial pressure to 52 mm Hg and 55 mm Hg in normotensive and hypertensive patients, respectively. Cardiac output (thermodilution) was maintained by low dose i.v. infusions of adrenaline (1-5 micrograms min-1). No differences in the haemodynamic response to induced hypotension were observed in hypertensive patients. Data were collected also from 987 consecutive patients (353 hypertensive and 634 non-hypertensive) undergoing total hip replacement. Patients with hypertension were significantly older (68 vs 60 yr; P less than 0.001) and had greater ASA ratings (P less than 0.001). The smallest recorded systolic pressures were reduced more in patients with hypertension (57% vs 52%, respectively; P less than 0.001). The mean duration of maintained intraoperative hypotension (100 and 98 min) and estimated intraoperative blood loss (278 vs 281 ml) were similar in each group. After operation, two patients developed myocardial infarctions. None developed acute renal failure or stroke. There were three deaths; one of a patient who had hypertension. This suggests that induced hypotension with extradural anaesthesia is a safe technique for patients with medically controlled hypertension undergoing total hip arthroplasty.

Effect of i.v. low-dose adrenaline and phenylephrine infusions on plasma concentrations of bupivacaine after lumbar extradural anaesthesia in elderly patients.

Thirty patients undergoing primary total hip replacement under lumbar extradural anaesthesia with 0.75% bupivacaine 25 ml were allocated randomly to receive either low-dose adrenaline or phenylephrine infusions i.v. throughout surgery. Haemodynamic measurements and arterial blood samples were obtained before the extradural injection and at 10, 20, 30, 40, 50, 60 and 90 min thereafter. Peak arterial plasma concentrations of bupivacaine were observed 10 min after extradural anaesthesia and were significantly lower in patients receiving adrenaline infusions. Cardiac output was significantly greater in patients receiving adrenaline infusions (P less than 0.01). It is postulated that the smaller circulating concentrations of bupivacaine observed in patients receiving adrenaline were caused by increased cardiac output and a greater volume of distribution than in patients receiving phenylephrine.

The effect of cardiac output on intraoperative blood loss during total hip arthroplasty.

BACKGROUND AND OBJECTIVES: It is not clear whether cardiac output affects intraoperative blood loss under epidural hypotensive anesthesia. METHODS: Thirty patients undergoing primary total hip arthroplasty were randomly assigned to receive intravenous infusions of either low-dose epinephrine or phenylephrine to maintain mean arterial pressure at 50 to 60 mm Hg throughout surgery under lumbar epidural anesthesia. Patients were monitored with radial artery and thermodilution pulmonary artery catheters. Hemodynamic parameters were measured every 10 minutes during surgery, and blood loss was estimated by a blinded observer weighing sponges. RESULTS: Mean arterial pressure was similar between groups. Cardiac output remained unchanged in patients receiving low-dose epinephrine but declined significantly in patients receiving phenylephrine (p = 0.0001). Blood loss was 228 and 236 mL in patients receiving low-dose epinephrine and phenylephrine, respectively (p = 0.86). No correlation was observed between cardiac output and blood loss at any point during surgery. CONCLUSIONS: Cardiac output is not a factor influencing blood loss during hypotensive epidural anesthesia in elderly patients undergoing primary total hip arthroplasty.