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A three-dimensional dynamic strength measuring equipment is described. This prototype was designed and fabricated to allow measurement of human isotonic strengths in various possible body configurations and at various locations in space.
The experiments reported here characterized the partial generalizations that prototype opiate drugs may produce in rats that are trained to discriminate 0.04 mg/kg of fentanyl from saline. Cyclazocine, nalorphine, ketocyclazocine and N-allylnormetazocine produced partial generalization with fentanyl; the same compounds also partially antagonized fentanyl. The fentanyl-like and the fentanyl-antagonist effects of these compounds occurred within similar ranges of dose. An orderly incompatibility was apparent between the agonist and antagonist effects produced by each drug; cyclazocine, for example, was unlikely to antagonize fentanyl in animals in which it produced generalization, whereas it did antagonize fentanyl in animals in which it produced no generalization. Cyclazocine, nalorphine, N-allylnormetazocine and naloxone produced either fentanyl-like or fentanyl-antagonist effects in all animals tested. A reliable relationship was apparent among the agonist and antagonist effects of different opiate drugs; rats that generalized cyclazocine also were likely to generalize nalorphine and ketocyclazocine and were relatively less responsive to cyclazocine, nalorphine, N-allylnormetazocine and naloxone as antagonists of fentanyl. The results point to the importance of a number of new methods in the analysis of drug discrimination data. Among these are the analysis of individual generalization data and the examination of agonist and antagonist effects of test drugs in the same animals. A parsimonious molecular interpretation of the data can be offered by assuming that morphine, ketocyclazocine, cyclazocine, nalorphine, N-allylnormetazocine and naloxone have affinity for, but differ in activity at, an opiate receptor where fentanyl acts to produce discriminative effects.
In each of two components of a multiple schedule, patas monkeys were required to respond on a right or left lever depending upon the stimulus combination (a color and a geometric form) presented. Reinforcement of a response in the presence of one stimulus (the form) was conditional upon the other stimulus (the color). The completion of a two-member chain of discriminations produced a food pellet. Errors produced a brief time-out. One component of the multiple schedule was a repeated-acquisition task where the discriminative stimuli for left- and right-lever responses changed each session (learning). In the other component, the discriminative stimuli were the same each session (performance). Morphine, ketocyclazocine and SKF 10,047 each produced dose-related decreases in overall rate of responding in both components of the multiple schedule. However, each drug affected the patterning of responding in a different manner. Across a range of doses which decreased response rate, neither morphine nor ketocyclazocine affected accuracy of the discriminations. In contrast, SKF 10,047 and its enantiomers produced a dose-dependent disruption of accuracy; errors were increased in the acquisition component at doses lower than those required to disrupt the discrimination in the performance component. The effects of the l-isomer of SKF 10,047 were generally comparable to those of the racemate. In comparison to the racemate, the d-isomer of SKF 10,047 was found to produce greater error-increasing effects in the acquisition component and smaller rate-decreasing effects in both components of the multiple schedule. In general, the effects of cyclazocine and pentazocine on both accuracy and rate of responding were comparable to those obtained with SKF 10,047. The results suggest that in patas monkeys, opioids with activity at the putative sigma receptor such as SKF 10,047, cyclazocine and pentazocine exert a dose-dependent disruptive effect on the accuracy of discriminations, an action not shared by prototypical mu and kappa opioid agonists, at doses which produce approximately equivalent rate-decreasing effects.
A penthrite grenade to replace cold harpoons in the Norwegian minke whale hunt was developed in 1983-1985. Data on survival times for 259 minke whales were collected from the trials in the 1984-86 hunting seasons, when 3 different prototypes were used. About 45% of the whales were killed instantaneously. The median survival time was 72 s. A substantially higher percentage of instantaneous deaths was recorded for penthrite grenades than for cold harpoons. The criteria for death were cessation of flipper movement, relaxation of the mandible, or sinking without any active movement. Some animals dived before the criteria could be controlled. If the central nervous system, heart, lungs or main vessels were damaged, a high percentage of the animals died instantaneously. In most cases, hits and detonations outside the thorax and central nervous system resulted in longer survival times than hits in the thorax. Survival time increased with whale size and range for animals not killed instantaneously. Marksmanship, technical and functional reliability of equipment and hunting techniques were all crucial to a good result. Better training of gunners, improved weapons and hunting equipment and more rapid reshooting of wounded animals would reduce the proportion of long survival times.
This is the first in a series of biological investigations using a porous implant fabricated by a novel process known as electrodischarge compaction (EDC). This process uses Ti-6A1-4V powder and electrical energy to construct a beaded porous implant without any compromise in physical characteristics, often found with conventional sintering. The purpose of this study was to evaluate the bone response in rabbit tibia of a porous titanium prototype implant fabricated by this new technique. One hundred forty-four porous EDC-fabricated implants were placed into the tibia of 36 New Zealand rabbits. Animals were placed into one of six time periods (2, 4, 8, 12, 18, and 24 weeks). At the appropriate time period, animals were killed, and bone ingrowth was evaluated qualitatively by light and scanning electron microscopy. Bone/implant interface bond strength was also measured. Slight bone ingrowth was observed as early as the two-week time period and increased in depth at each time period for the duration of the study. Implant/bone bond strength was measurable at four weeks and continued until reaching a plateau at week 12. The results of this study suggest that this novel EDC implant may be suitable for continued development of an easily fabricated, cost-effective dental implant.
Based on the results obtained in two dimensions or extrapolated into three dimensions by current medical imaging techniques (CT scan, magnetic resonance imaging), it is possible, under certain conditions, to create hard complex anatomical specimens, of obvious value in cold surgery. Two successive approaches of design and manufacture of an orbital cavity prototype are presented, as a preliminary to industrial productions soon to be released onto the market.
Studies were focused on two attenuated serotype 1 Marek's disease (MD) vaccine viruses, CVI988/Rispens (passage 42) and R2/23 (passage 105). Both serotype 1 vaccine viruses provided much higher levels of protection than the prototype MD vaccine, turkey herpesvirus (HVT); the best protection was generally provided by CVI988/Rispens when compared with other vaccines. The efficacy of neither serotype 1 vaccine was improved by mixture with viruses of other serotypes (synergism). No differences between the two serotype 1 vaccines were revealed by cross-neutralization tests, thus excluding preferential in vivo neutralization by maternal antibodies as an explanation for differences in protective efficacy. Neither vaccine strain induced MD lesions or reduced growth rates in 8- or 18-week trials. Neither virus depressed humoral or cellular immune responses to antigenic challenge at 3 or 15 days after vaccination. Both virus strains exhibited altered characteristics during serial backpassage; R2/23 acquired increased oncogenic potential, and CVI988/Rispens acquired the potential for increased viremia titers, accompanied by an increased frequency of both histologic nerve lesions and gross thymic atrophy. During backpassage trials, contact spread was not observed for R2/23 and, surprisingly, seemed relatively limited for CVI988/Rispens. Studies on these two serotype 1 strains generally support the safety and efficacy of the serotype 1 class of MD vaccines.
BACKGROUND AND OBJECTIVES: To provide patients with better postoperative pain relief, the authors developed a prototype computer-controlled infusion pump capable of establishing a steady drug plasma concentration based on patient needs. METHODS: A two-compartment pharmacokinetic model was used to compute the required infusion scheme. Using known pharmacokinetic parameters, the model and the pump's accuracy were studied in four dogs. In the first part of the study, the morphine pharmacokinetic profile of each dog was analyzed and used to develop the parameters of a model tailored to that particular dog. In the second part, this tailored model was implemented to test whether the infusion device was able to achieve the desired concentration profile. RESULTS: The computer-controlled infusion device was able to achieve all the desired plasma concentrations. CONCLUSIONS: These data suggest that it is possible to refine postoperative pain management with adaptive computer algorithms implemented to establish stable plasma analgesic concentrations and to automatically wean the analgesic over time.
The recent progress in endoscopic surgery, which is highlighted by the complexity of fundoplication, stomach surgery and colorectal surgery, has revealed major restrictions with difficult surgical manipulations. Mobilisation, dissection and suturing techniques are hampered mainly by the limited degrees of freedom of the conventional rigid instruments (translation along and rotation around the longitudinal axis and the limited play in the access channel). The frequent interchange of instruments such as coagulation forceps, scissors and suction-irrigation probe is time-consuming. We have established an interdisciplinary development model with the aim of improving surgical technology, instrument systems, the operation theatre and its environment. Concepts of electronic instrument control and sensoric feedback, and the features of the surgical man-machine-interface are described. The first prototypes of an intelligent steerable instrument system, ISIS, and its optional effectors, e.g. semiautomatic sewing device and multifunctional coagulation instrument, were tested in phantom and animal experiments. System analysis will lead to specially designed operating theatres (minimal invasive surgical operating system MINOS).
The inadequate analysis of medical research data, due mainly to the unavailability of local statistical expertise, seriously jeopardizes the quality of new medical knowledge. Data Explorer is a prototype Expert System that builds on the versatility and power of existing statistical software, to provide automatic analyses and interpretation of medical data. The system draws much of its power by using belief network methods in place of more traditional, but difficult to automate, classical multivariate statistical techniques. Data Explorer identifies statistically significant relationships among variables, and using power-size analysis, belief network inference/learning and various explanatory techniques helps the user understand the importance of the findings. Finally the system can be used as a tool for the automatic development of predictive/diagnostic models from patient databases.
A prototype inline intravenous final filter with a large filtration area and an air-elimination feature was evaluated. Adequate and uniform flow rates were maintained with infusion solutions containing cephalothin and ampicillin, while with oxytetracycline, flow rates decreased significantly. Challenging the unit with air demonstrated the suitability of the air-elimination system. In a brief clinical trial on 53 patients, the unit appeared easy to use and gained the acceptance of nurses, pharmacists and physicians.
Transcatheter closure of a secundum atrial septal defect was attempted using a prototype clamshell septal umbrella closure system in 11 patients (six males, five females, aged 4.4-15.0 years and weighing 16-51 kg). The balloon stretched atrial septal defects were 10.3 to 20 mm in diameter, and 23 to 40 mm diameter umbrellas were used. All patients improved clinically after the procedure. Fixed splitting of the second heart sound disappeared after closure in 10 patients, systolic murmur disappeared in nine, diastolic rumble in nine, and paradoxical ventricular septal motion in seven. Doppler color flow imaging immediately after implantation showed significant residual shunt in all patients; however, no shunt flow was observed in seven patients and minimal residual shunt was present in four one year after the procedure. Nine of 11 umbrellas demonstrated fracture of the stainless steel arm confirmed by chest radiography and cinefluorography. Arm fracture occurred between 1 week and 12 months after implantation. None of the devices were dislodged and no other complications were noted despite the fractures. Transcatheter closure of atrial septal defect is a feasible and useful procedure but the present device needs further modification.
This paper describes the evolution of the Wheelchair Aerobic Fitness Trainer (WAFT), a wheelchair ergometer developed for determination of aerobic capacity and the diagnosis of coronary artery disease in lower limb disabled persons whose mobility depends primarily on the manual wheelchair. The device was originally developed for use in research studies to determine peak exercise capacity in persons with spinal cord injuries and other lower limb disabilities and to formulate associated graded exercise stress test protocols. In subsequent research, the device was incorporated into a specially designed testing station for the detection of coronary artery disease in persons who cannot adequately undergo treadmill or cycle ergometry testing because of lower limb disabilities. Based on the usefulness of the device for both rehabilitation and diagnostic purposes, the WAFT has been brought into the technology transfer process of the Department of Veterans Affairs Rehabilitation Research and Development Service. Under a contract with Packer Engineering, Inc., Naperville, IL, development of a preproduction version of the device and six units for field evaluation has commenced. The preproduction prototype of the WAFT has incorporated numerous improvements over the original device and promises to expand the potential for future research, rehabilitation, and diagnostic applications.
Spontaneous mutations in human somatic cells occur far more often than normal in individuals with Bloom syndrome. The basis for understanding these mutations and their developmental consequences emerges from examination of BS at the molecular, cellular, and clinical levels. The major clinical feature of BS, proportional dwarfism, as well as its major clinical complication, an exceptionally early emergence of neoplasia of the types and sites that affect the general population, are attributable to the excessive occurrence of mutations in somatic cells. Here, the following aspects of BS are discussed: (i) the BS phenotype; (ii) neoplasia in BS, including the means--the Bloom's Syndrome Registry--by which the significant risk for diverse sites and types of cancer in these patients was revealed; (iii) the biological basis for the cancer proneness of BS; and, finally, (iv) the significance for both basic human biology and clinical medicine of BS as the prototype of somatic mutational disease.
This paper describes current research into the creation of solid models which replicate anatomical structures using rapid prototyping techniques. Stereolithography is particularly efficient in the production of highly-complex structures. This technique was applied to the fabrication of a plastic model of a human skull. A geometric definition of the object was obtained by transferring the three-dimensional medical image volume (x-ray CT) and processing the data on a computer graphics workstation. A 3-D biomedical visualisation software package (ANALYZETM) was used to perform segmentation of structures. A 3-D triangular-mesh representation of the selected structure was calculated and converted to a format suitable for processing and construction using stereolithography (SLA). Improvements in the quality of the anatomical model produced will result from improved data processing techniques. Future work is proposed to investigate the influence of imaging parameters and data processing techniques on the resultant plastic models.
Three alternative toothbrushes were investigated in a double blind Latin Square repeated measures design study for their relative efficiency at removing plaque 'in vivo'. A prototype filament suspension design toothbrush was tested, with the suspension mechanism both active and inactive, against a conventional toothbrush. Following an initial control plaque score, subjects were ordered by oral hygiene levels and randomly allocated to each of the three test groups. The trial was made up of three periods of 14 days consisting of four days of no brushing followed by 10 days of brushing with each of the three toothbrushes. All plaque scores were recorded using the Greene and Vermillion Index of Oral Hygiene and plaque scores were recorded for each patient at the start, four days later and at the end of each 14-day period. There were no significant differences in the quantity of plaque remaining after brushing with any of the brushes tested in this study. Ignoring the toothbrush used, the end brushing average plaque scores for period 1 were found to be higher than the control plaque scores. It is suggested that this resulted from the patients finding new toothbrushes less comfortable to use initially but following a period of accommodation and adjustment, end brushing plaque levels in subsequent periods returned to near the same level as the control plaque score.
Based upon previous research on the relation between hip prosthesis designs and strain distributions in a proximal femur model, a prototype of a "physiological" hip prosthesis was designed and manufactured. Strain gauge measurements on a dry femur before and after implantation of this prosthesis were made in different loading conditions simulating one-legged stance with and without torsional loading and two-legged stance. The strains in the outer cortex were within 10% of the physiological values along the whole medial side in all measurement conditions.
Optimal treatment of cancer depends upon early diagnosis. With an aging retiree and dependent population, cancer diagnosis and management must be addressed by military medical treatment facilities (MTFs) in a coherent and cost-effective fashion. A prototype multidisciplinary cancer screening clinic is described which interdigitated MTF and local American Cancer Society resources. Sites screened included breast, prostate, skin, cervix, and oral cavity, with mammograms, prostate-specific antigens, PAP smears, and physical exams, as appropriate. Of 194 patient contacts over a 4-hour period, eight cancers were found and subsequently treated (five skin, three prostate). Patient selection criteria, screening results by site, lessons learned, and recommendations for future clinics are discussed. The multidisciplinary screening clinic is readily applicable to the MTF setting, cost-effective, and provides an invaluable service to eligible patients.