Dexterous helical magnetic robot for improved endovascular access.

Treating vascular diseases in the brain requires access to the affected region inside the body. This is usually accomplished through a minimally invasive technique that involves the use of long, thin devices, such as wires and tubes, that are manually maneuvered by a clinician within the bloodstream. By pushing, pulling, and twisting, these devices are navigated through the tortuous pathways of the blood vessels. The outcome of the procedure heavily relies on the clinician's skill and the device's ability to navigate to the affected target region in the bloodstream, which is often inhibited by tortuous blood vessels. Sharp turns require high flexibility, but this flexibility inhibits translation of proximal insertion to distal tip advancement. We present a highly dexterous, magnetically steered continuum robot that overcomes pushability limitations through rotation. A helical protrusion on the device's surface engages with the vessel wall and translates rotation to forward motion at every point of contact. An articulating magnetic tip allows for active steerability, enabling navigation from the aortic arch to millimeter-sized arteries of the brain. The effectiveness of the magnetic continuum robot has been demonstrated through successful navigation in models of the human vasculature and in blood vessels of a live pig.

Measuring colloidal forces with the magnetic chaining technique.

In 1994 Leal Calderon et al. (Phys. Rev. Lett. 72, 2959 (1994)) introduced the magnetic chaining technique to directly probe the force-distance profile between colloidal particles. In this paper, we revisit this approach in two ways. First, we describe a new experimental design which allows us to utilize sample volumes as low as a few microliters, involving femtomoles of surface active macromolecules. Secondly, we extensively describe the characterization and preparation of the magnetic colloids, and we give a quantitative evaluation of performance and resolution of the technique in terms of force and interparticle separation.

Characterizing pixel and point patterns with a hyperuniformity disorder length.

We introduce the concept of a "hyperuniformity disorder length" h that controls the variance of volume fraction fluctuations for randomly placed windows of fixed size. In particular, fluctuations are determined by the average number of particles within a distance h from the boundary of the window. We first compute special expectations and bounds in d dimensions, and then illustrate the range of behavior of h versus window size L by analyzing several different types of simulated two-dimensional pixel patterns-where particle positions are stored as a binary digital image in which pixels have value zero if empty and one if they contain a particle. The first are random binomial patterns, where pixels are randomly flipped from zero to one with probability equal to area fraction. These have long-ranged density fluctuations, and simulations confirm the exact result h=L/2. Next we consider vacancy patterns, where a fraction f of particles on a lattice are randomly removed. These also display long-range density fluctuations, but with h=(L/2)(f/d) for small f, and h=L/2 for f→1. And finally, for a hyperuniform system with no long-range density fluctuations, we consider "Einstein patterns," where each particle is independently displaced from a lattice site by a Gaussian-distributed amount. For these, at large L,h approaches a constant equal to about half the root-mean-square displacement in each dimension. Then we turn to gray-scale pixel patterns that represent simulated arrangements of polydisperse particles, where the volume of a particle is encoded in the value of its central pixel. And we discuss the continuum limit of point patterns, where pixel size vanishes. In general, we thus propose to quantify particle configurations not just by the scaling of the density fluctuation spectrum but rather by the real-space spectrum of h(L) versus L. We call this approach "hyperuniformity disorder length spectroscopy".

[Incidence of biological intravascular coagulation in legal induced abortions]. / Incidence des coagulations intravasculaires biologiques au cours des interruptions volontaires de grossesse.

A prospective study was designed to evaluate coagulation abnormalities induced by early abortion (before ten weeks of pregnancy). Fifty-two women underwent suction abortion, under diazepam-fentanyl anaesthesia with spontaneous ventilation; they were screened for coagulation parameters before and after surgery. Eight tests were carried out: prothrombin time, activated partial thromboplastin time (APTT), thrombin time platelet count, fibrinogen levels, fibrin split products, fibrin soluble complexes and euglobulin lysis time. Results were consistent with activation. Consequences were limited and one general test (APTT) was not significantly modified. Suction abortion, even performed in early pregnancy, exposed to biological disseminated intravascular coagulation with a general risk of venous thrombosis.

PIP: A prospective study was designed to evaluate coagulation abnormalities induced by early abortion (before 10 weeks of pregnancy). 52 women underwent suction abortion, under diazepam--fentanyl anesthesia with spontaneous ventilation; they were screened for coagulation parameters before and after surgery. 8 tests were carried out: prothrombin time, activated partial thromboplastin time (APTT), thrombin time platelet count, fibrinogen levels, fibrin split products, fibrin soluble complexes and euglobulin lysis time. Results were consistent with activation. Consequences were limited and 1 general test (APTT) was not significantly modified. Suction abortion, even performed in early pregnancy, exposed the patient to biologically disseminated intravascular coagulation with a general risk of venous thrombosis. (author's modified)

Magnetic force probe for nanoscale biomolecules.

We present a new technique to measure the mechanical properties of small biomolecules. This technique uses long range repulsive colloidal forces together with magnetic attraction as a force probing tool. The biomolecules are grafted between superparamagnetic particles, which are regularly spaced within long chains maintained by an external magnetic field. Varying the magnetic field results in compression or extension of the molecules between the particles. In order to demonstrate this technique we use, as a size controlled model molecule, a short double stranded DNA (151 base pairs) for which the force-extension law is determined and found in agreement with existing predictions.

The underrated benefits of oral contraception: consequences of pregnancy and induced abortion in teenagers.

If complications occur within a pregnancy planned and brought to term, they often can be dealt with and accepted. They are even more traumatic when they occur in an unwanted pregnancy that could have been prevented through contraception. Teenagers, because of their physical and psychological immaturity and also because of their social environment, seem to suffer with undue frequency from the complications of induced abortion. Its result, for the teenager, is a handicapped future in comparison to other women. Hence, access to contraception is important for all women, and especially for teenagers, in order to avoid such prejudicial situations. It is important, then, to prescribe oral contraception for its efficacy and its short- and long-term innocuousness. Because of her immaturity, the pregnant teenager is at risk: of spontaneous abortion, pre-eclampsia, anemia, hemorrhage, and prematurity. She is also at risk because of the social difficulties she will be facing. This is particularly true in families from developing countries. From birth, the child is also at risk: of low birth weight for the term, mortality in the first year of life, and all risks linked to abandonment, or education by a third party. In a proportion of 13 to 30% in western countries and in a proportion of 3% in East Asia or in Northwest Africa (Maghreb), induced abortions are a reflection of the following: early sexual activity without contraception even if fertility is still low in very young teenagers, absence of social protection or social independence, refusal of forced marriage, and presence or absence of liberal legislation.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: Adolescent pregnancy rates are higher among US teenagers than among Swedish teenagers, even though there is a higher proportion of teenage virgins in the US. A leading reason for this discrepancy is that contraceptive use among sexually active US teenagers, especially those who have recently become sexually active, is quite low. Even teenagers using contraceptives experience unwanted pregnancy due to incorrect or inconsistent use of a method, especially barrier methods. Thus, access to abortion services and postcoital contraception are needed. The reasons teenagers often delay abortion are denial of pregnancy, irregular menses and inexperience about signs of pregnancy, fear of telling parents, and not knowing where to seek help. In most countries, adolescents comprise a considerable percentage of abortion patients. They are also at high risk of suffering some abortion complications, one reason being they tend to undergo abortion at later gestational ages than older women. For example, 2nd trimester abortions pose a risk 3-10 times greater than 1st trimester abortions. Teenagers under 17 years old and undergoing suction curettage are at greater risk of cervical injury than older women. On the other hand, teenagers do not face higher risk of other abortion complications than do older women. Adolescents undergoing abortions in developing countries face greater risk of complications, especially mortality, due to certain cultural or sanitary conditions. An unwanted pregnancy places teenagers at considerable risk, e.g., delivering a low birth weight child at high risk of mortality. These findings indicate the need for sexually active teenagers to have accurate information on reproduction and contraception and access to family planning services at an early age. Oral contraceptives (OCs) are the most effective contraceptive for adolescents and provide other benefits as well. Physicians need to promote OC use and communicate OCs' noncontraceptive benefits to teenagers because they often are unable to perceive them. Physicians also need to stress that OCs do not protect against sexually transmitted diseases and AIDS.

Versatile microsecond movie camera.

A laboratory-type camera is readily assembled using the following off-the-shelf components: a 3-mW He-Ne laser; an acoustooptic modulator; an electromechanical beam deflector; and a video (TV) tape recorder. The present camera is distinct in its operation in that submicrosecond laser flashes freeze the image motion while still allowing the simplicity of (millisecond range) electromechanical image deflection. The gating and pulse delay circuits of an oscilloscope synchronize the modulator and scanner relative to the subject being photographed. The pictures consist of a 3-64 frame sequence; the interframe time ranged from ~1 microsec to >1000 microsec. Video recording provides immediate monitoring of the picture quality and accuracy of synchronization. A number of variations are available for particular applications. For example, one can change the electrical pulsing to produce either streak or stroboscopic pictures instead of frames, and film can be substituted for video recording in order to retain more details of the image.

Communicating P & T guidelines: how one committee meets the challenge.

The P & T Committee's role in advocating rational therapeutics is addressed in this exclusive Hospital Formulary interview with Richard Dreyfus, MD, and Fredrick Bender, PharmD, P & T Committee chairman and secretary at Saint Vincent Health Center in Erie, PA. This Committee has evolved beyond providing strictly formulary review and regulation and is now involved in utilization review of certain drugs in an effort to maximize their therapeutic potential. They stress the importance of communicating and educating the medical staff with regard to formulary issues and discuss the methods they find to be most effective. Methods for maintaining altered prescribing patterns, drug utilization review, adverse drug reaction reporting, and formulary review are highlighted.

[Induced abortion under acupunctural analgesia (25 cases)]. / Analgesie acupuncturale au cours de l'I.V.G. (A propos de 25 cas).

PIP: The article reports on the first 25 cases of induced abortion practiced under acupunctural analgesia in France. 5 points were touched on the body, and 3 on the ear. The 25 patients, all between 19-40, did not feel any pain, except in one single case. Bleeding was minimal, duration of intervention about 10-15 minutes, and duration of hospitalization very short, about 2h.30'. The major advantages of analgesia through acupuncture are its total safety, and, especially, the fact that it leaves the patient totally conscious, establishing a better relationship between patient and doctor.^ieng

[Difficulties with contraception and voluntary pregnancy termination: a survey carried out at the hopital Saint-Louis]. / Contraception difficile et IVG, a propos d'une enquete realisee a l'hopital Saint-Louis.

PIP: A 1985 prospective study at the Saint-Louis Hospital in Paris indicated that 138 of 252 abortions (53.8%), were associated with problems of contraception and 114 were not. The percentages of cases involving problems with contraception varied from 34% to 58.2% according to the physicians participating in the study. Despite the very subjective nature of the estimates, at least 1/3 of abortions at this hospital are associated with difficulties in contraception. In 64 of 138 cases, the problems were caused by psychological factors, including ambivalent desire for pregnancy in 24 cases, psychological refusal of contraception in 15 cases, psychological immaturity in 4 cases, various psychological problems in 4 cases, and a psychological factor associated with some other difficulty in 17 cases. Among the various psychological problems were 1 woman using abortion as a contraceptive method who had undergone 9 abortions and 1 case of cultural resistance to contraception. Among the 17 cases where the psychological problem was associated with some other difficulty there were 7 cases of ambivalent desire for pregnancy, 4 cases of psychological refusal of contraception, and 6 cases of various psychological problems. Among these cases, available contraceptive methods were contraindicated or poorly tolerated apart from the psychological difficulty. Among the 74 cases of contraceptive difficulty not associated with psychological factors were: 12 cases of nulliparity and nontoleration of combined oral contraceptives (OCs); 22 cases of nulliparity and OCs contraindicated or inadvisable; 22 cases of OCs and IUDs contraindicated, inadvisable, or refused; 5 cases of IUD failure with OCs not possible; 2 cases of failure of local methods with other methods not possible; and 11 cases of various difficulties including 4 of difficulties of communication for linguistic reasons and 7 cases of repeated forgetting or incorrect taking of pills. It is not known whether the 252 cases in this survey are representative of the entire population. Problems in contraception are common among women seeking abortions and appear to affect at least 1 in 3 such women. The psychological factor is very significant among these women. Cases of contraceptive problems apart from psychological factors have primarily referred to nulliparous women unable to take pills and other women unable to use either OCs or IUDs. Vaginal contraceptive methods are not used as much as they could be in such cases. 4 cases are briefly described to illustrate the problems some women encounter in finding a suitable contraceptive method.^ieng

Fatalities associated with an acute overdose of glutethimide (Doriden) and codeine.

Abuse of the oral combination of glutethimide (DORIDEN) and codeine, commonly referred to as "sets", in the northwest Pennsylvania area is reviewed. Nine fatalities have been reported in the Erie area from 1985-87 due to acute toxicity with this combination. The glutethimide/codeine combination reportedly produces a euphoric effect comparable to intravenous heroin but is longer lasting. Age of the victims ranged from 18 to 37 years. In all cases there was a history of chronic intentional "sets" abuse by the victims prior to death. The 9 fatalities due to this combination of prescription drugs is unusually high for this area considering the population and rural nature of the Erie community. Although the use of "sets" has been reported occasionally in other localized areas of the country, no other significant use has been reported in Pennsylvania.