Spontaneous association between opioid receptors and GTP-binding regulatory proteins in native membranes: specific regulation by antagonists and sodium ions

High affinity GTPase in membranes from NG108-15 cells was differentially affected by opioid competitive antagonists; one type of antagonist [( N,N'-diallyl-Tyr1-Aib2,3]Leu-enkephalin) reduced the basal rate of GTP hydrolysis, whereas a second type (MR 2266) produced no changes. The inhibitory effect of the "active" antagonist was stereospecifically reversed by the "inactive" antagonist, indicating that it was receptor mediated. This suggests that part of basal GTPase activity in this system results from a spontaneous interaction between opioid receptors and GTP-binding proteins (G proteins) and that some antagonists exhibit negative intrinsic activity by hindering such an interaction. The inhibitory effect of the antagonist was minimal in the presence of Na+ and maximal when Na+ was replaced by K+ in the reaction. When the ratio [Na+]/[K+] was progressively increased at constant [Cl-], total GTPase activity (i.e., net difference between activity stimulated by agonist and that inhibited by antagonist) did not change, but the activity measured in the absence of ligand was selectively decreased. Thus, Na+ does not alter the total proportion of G proteins that can be activated by ligand-occupied receptors and instead regulates the interaction between receptor and G protein in the absence of ligand. Upon examination of several opioid agonist and antagonists, we found an inverse relation between the intrinsic activity (either negative or positive) of each ligand and the sensitivity to Na+ of the GTPase elicited upon occupation of the receptor by that ligand. Sodium-mediated and ligand-mediated regulations of GTPase had identical requirements for Mg2+ [( Mg2+]free greater than 10 microM), and were both abolished with a similar potency by pertussis toxin. There was no effect of Na+ on the basal rate of GTP hydrolysis of Gi/Go purified from bovine brain. However, addition of these proteins to membranes prepared from cells that had been previously exposed to pertussis toxin partially restored both receptor- and sodium-mediated regulations of GTPase in parallel and in a concentration-dependent fashion. We conclude that sodium ions play a key role in the mechanism underlying the spontaneous interaction between "empty" receptors and G proteins in intact membranes.     

The acceptance of SARS-CoV-2 rapid antigen self-testing: A cross-sectional study in China

Compared with the nucleic acid amplification test (NATT), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid antigen self-testing (RAST) has advantages in speed and convenience. However, little is known about people's acceptance and influencing factors for SARS-CoV-2 RAST. A cross-sectional study was conducted from April 21 to 30, 2022 in China. The χ² test and multivariate logistic regressions were used to identify the influencing factors. The structural equation model was used to test the extended protective motivation theory (PMT) model hypotheses. Among the total of 5107 participants, 62.5% were willing to accept the SARS-CoV-2 RAST. There were significant differences in acceptance among different residences (p < 0.001), educational level (p < 0.001), occupation (p < 0.001), monthly income (p < 0.001), travel frequency (p < 0.05), and feelings about NATT (p < 0.001). Response efficacy (β = 0.05; p = 0.025) and self-efficacy (β = 0.84; p < 0.001) had a positive effect, while response cost showed a negative effect (β = −0.07; p < 0.001). The public's major concerns about SARS-CoV-2 RAST are its reliability, testing method, price, and authority. Overall, a moderate intention to use SARS-CoV-2 RAST was found among the Chinese population. The extended PMT can be used for the prediction of intention to accept the RAST. We need to take measures to increase people's acceptance of SARS-CoV-2 RAST.     

COMPLICATIONS IN LAPAROSCOPIC GYNECOLOGIC SURGERY

Objective. To investigate retrospectively the complications and associated factors of gynecological laparescopies.Methods. 1769 laparoscopic surgeries were carried out from January 1994 to October 1999 at our department. The procedures included 1421 surgeries of ovary and tube, 52 myomectomies and 296 cases of laproscopic-assisted vaginal hysterectomy (LAVH). A total of 312 patients had a history of prior laparotomy (17.6%). Results. Complications occured in 34 cases, the overall complication rate was 1.92%. Unintended laparotomies occured in 6 cases(0.34% ). 12 complications were associated with insertion of Veress needle or trocar and creation of pneumoperitoneum, including 5 severe emphysema and 7 vascular injuries, this figure represents 35.3% of all complications of this series. Five intraopemtive complications (14.7 % ) occured during the laparescopic surgery (3 severe bleedings, one bladder injury and one skin bum of leg caused by damaged electrode plate), laparotomy was re-quired in four of these cases. Seventeen complications occured during postoperative stage: 2 intraperitoneal hemor-rhages needing laparotomy, 2 bowel injuries, 4 nerve paresis and 9 febrile morbidities. Cordusions. Operative gynecologic laparoscopy is associated with acceptable morbidity rate, but can not be over-looked. Complication rate seems to be higher in advanced procedures such as LAVH.     

Prevalence of sexually transmitted diseases in juvenile prostitutes and street youth

Four groups of adolescents - 35 juvenile prostitutes, 36 street youth, 31 monogamous sexually active adolescents and 35 non-sexually active adolescents - were studied between January 1, 1988 and December 31, 1988 for the presence of sexually transmitted diseases and other genital pathogens. The high prevalence of sexually transmitted diseases found in the juvenile prostitutes (Neisseria gonorrhoeae, 49%; Chlamydia trachomatis, 83%) is in contrast to other studies, which document much lower rates of infection. This could be due to the fact that there are few studies done on juvenile prostitutes as a well defined group. Despite high risk sexual behaviour, the consistent use of contraception was low. No contraceptives were used by 57% of the juvenile prostitutes and 85% of the street youth. None of the adolescents sought medical attention although 48% of the juvenile prostitutes and 53% of the street youth had genital symptoms. It appears that the present public health education and health care delivery do not reach this high risk population.     

Can parturients distinguish between intravenous and epidural fentanyl?

We tested the hypothesis that the sedative, euphoric, and analgesic effects of intravenous fentanyl would distinguish intravenous from epidural administration. One hundred ASA I and II labouring parturients received 100 μg fentanyl either iv or via an epidural catheter in a double-blind, randomized, crossover fashion. Nineteen anaesthetists (8 staff and 11 residents) participated and correctly guessed the route of administration of the fentanyl in 61/66 intravenous doses and in 69/75 epidural doses yielding a sensitivity of 92.4%, a specificity of 92.0%, a positive predictive value of 91.0%, and a negative predictive value of 93.2%. Of the 41 patients that were crossed over, 38 (92.7%) were able to detect a difference between the routes of administration. Most patients experienced prompt, short-lived symptoms with iv fentanyl but no important differences in fetal heart rate pattern or in maternal desaturation were seen between the groups. This study suggests that subjective symptoms will accurately distinguish intravenous from epidural fentanyl administration in labouring parturients (P < 0.001), and should serve as a safe and reliable intravenous test dose for epidural anaesthesia in the obstetric population.     

Principles of screening

Preventive medicine is an increasingly important area of clinical practice. Conceptually, preventive medicine involves three tasks of the clinician: screening, counseling, and immunization/prophylaxis. This opening article reviews some of the basic tenets underlying screening including basic epidemiologic principles, characteristics of a good screening situation, barriers to screening, and some of the potential hazards of screening.     

Contrast enhanced MRA of peripheral arteries with the automatic "floating table".

Magnetic resonance angiography (MRA) is increasingly used as a non-invasive alternative to digital subtraction angiography (DSA). Besides plain time-of-flight (TOF) and phase contrast (PC) MRA a new MRA technique using positive contrast agent has been introduced recently. A fast 3D gradient-echo sequence is applied to reach a significant reduction of measurement time for acquisition of the MRA within the first pass of the contrast agent, thereby avoiding venous overlap. A significant progress was yielded by MR systems allowing manual table movement for examination of the pelvis and the lower limbs in one examination with a single contrast agent bolus. However, in this case it is necessary to have a coworker in the examination room moving the table manually. In this paper we report a prototype system which allows automatic table movement ("floating table"). Using this novel system we examined a patient with an aneurysm of the abdominal aorta and peripheral arterial occlusive disease (PAOD). Diagnostic results of contrast enhanced MRA and DSA were equivalent. In summary, the automatic floating table system introduced in this paper allows comfortable non-invasive examination of pelvic and lower limb arteries. The value of this technique in comparison to DSA has to be determined in future studies.     

Evaluation of combined neurosurgical and trans-facial excision of extensive rhinosinus tumors infiltrating the anterior skull base

Rhino-sinusal tumors are rare, representing approximately 0.3% of all cancers and 3% of tumors of the upper respiratory and digestive tracts. In cases in which the tumor has infiltrated the anterior cranial base, the treatment of choice is a surgical resection by combined neurosurgical and transfacial approach giving the best possible exposition for the excision. The resection is associated with various reconstruction techniques according to the extent of the defect. Sixteen patients with rhino-sinusal tumors extending to the anterior cerebral cavity were operated at the ENT clinic of the CHUV in Lausanne between 1977 and 1997. The transfacial and neurosurgical combined approach is rarely curative (30% 5 years survival rate, 80% local recurrence during follow-up), but is still justified, given that its disabling side-effects are scarce. It offers an acceptable quality of life and prevents complications inherent to the natural development of tumors. Pre- or postoperative radio- and chemotherapy, as well as skull base reconstructions using bone grafts or a micro-anastomosed flap give rise to complications which worsen significantly the overall prognosis and should therefore be avoided as much as possible. Still, this heavy surgery remains indicated, because it prevents the numerous complications of the natural course of the disease and offers an acceptable quality of life with only few side-effects.     

Visually guided exploration in Huntington disease

We compared 24 patients in various stages of Huntington disease (HD) with 26 control patients free from cerebral disorders using a simple visual saccadic tracking test. The two groups were well matched in regard to age, sex, verbal IQ and years of schooling. Test results differed widely. On a time versus error plot, sensitivity (96%) and specificity (100%) were high and the results did not depend on age, education, or disease duration, although an influence of disease stage could be observed. This study shows that a simple saccadic tracking task may be useful in detecting visuomotor disturbances in HD.     

Analysis of premature termination in inpatient psychosomatic rehabilitation based on epidemiologic data from two hospital companies

Premature termination of inpatient psychotherapy can have multiple, mostly negative, effects for patients, therapists, clinics, insurance companies, and employers, but research regarding inpatient settings is still deficient. The analysis of two sets of data of four different rehabilitation clinics from two different hospital companies (2699 and 2215 patients, respectively), aimed at possible predictors and outcomes of premature termination. We found ratios of premature termination of 8.3% and 14.7%, respectively. Especially young patients under 30 years of age and patients with eating and personality disorders were more likely to terminate inpatient treatment prematurely. Treatment outcome as rated by therapists was in significantly fewer cases among premature terminators than among successful terminators improved. The results seem to indicate, that assignment to inpatient psychotherapy can be optimized. For a better understanding of the process of premature termination more theory guided prospective and followup studies are necessary.