Enumerative and binomial sampling plans for armored scale (Homoptera: Diaspididae) on kiwifruit leaves.

The spatial dispersion of armored scale insects; greedy scale, Hemiberlesia rapax (Comstock); and latania scale, Hemiberlesia lataniae (Signoret), was investigated on kiwifruit, Actinidia deliciosa (A. Chevalier) C. F. Liang et A. R. Ferguson, leaves in New Zealand. A universal description for dispersion was determined using Taylor's power law, which encompassed a wide range of different orchards, blocks, block sizes, sampling times, scale control practices, regions and seasons. Scale density significantly altered dispersion, especially at the high densities found on unsprayed kiwifruit. Most commercially managed kiwifruit blocks had low densities of <0.5 scale per leaf and had a slightly aggregated scale dispersion. Wilson and Room's binomial model, which incorporates a clumping pattern as a function of density, gave a significant relationship between the proportion of infested leaves and scale density. The optimal leaf sample sizes were estimated for predetermined levels of sampling reliability. Where population estimates require a high degree of precision and enumerative sampling methods are used, 2,500 leaves should be sampled when scale densities are near the current spray threshold of 4% infested leaves and 500 leaves at 20% infested leaves. For management-decision sampling, where a lower level of precision was acceptable, enumerative sampling would require that 400 leaves be sampled at 4%; or 85 leaves at 20% infested leaves. With binomial sampling to achieve an equivalent level of precision an increased sample size of 6-11% is required.

Assisted reproduction and reproductive rights: the case of in vitro fertilization.

In vitro fertilization (IVF) and other assisted reproduction technologies (ARTs) have become widely accepted as therapy for a wide array of fertility problems and accompanied by the rapid expansion of clinics that provide full range of ARTs. Although these technologies undoubtedly offer benefits for some individuals, they raise important questions over reproductive rights to safe and effective treatment as well as access. This article analyzes current data concerning the safety, effectiveness, and cost of IVF. It concludes that IVF and related techniques have been transformed too rapidly and easily from experimental to therapy status, despite evidence that suggests considerable caution is warranted. Unfortunately, the widespread diffusion of IVF has preceded rather than followed firm evidence of its value in extending the reproductive rights of women and couples. Resources might better be directed toward prevention of fertility problems and discovering the causes of infertility.

Teaching biomedical policy to undergraduates.

Biomedical choices are emerging as critical policy issues of the 1980s. Political pressures for cost containment, trends toward corporate medicine, and continuing problems of access and equity ensure biomedical issues a prominent place on the policy agenda. Students of political science should be familiar with the array of biomedical technologies that currently are challenging the tenets of medicine as well as the capacity of political institutions to resolve the resulting policy dilemmas. Based on this, a course in biomedical policy is overdue. This article outlines a course which is designed to clarify the public policy dimensions of biomedicine and develop analytical skills in the students so that they can better cope with these issues of public and personal importance. It describes some of the approaches and methods that I have found useful and summarizes a few of the problems one might expect to encounter in teaching biomedical policy.

Valve replacement in the elderly: a long term appraisal.

From July 1972 through July 1983, 360 consecutive patients 70 years of age and older (mean age 74.1; range 70-88 years) underwent 362 valve replacement procedures. There were 122 isolated aortic valve replacements (33.7%; Group I); 70 isolated mitral valve replacements (19.3%; Group II); and 170 patients had combined procedures (47.0%; Group III), which included the replacement of at least one valve. Eighteen patients (5.0%) had previous cardiac surgery. Thirty-two patients (8.8%) were operated as emergencies. Three hundred and thirty-two (86.5%) of all valves implanted were porcine heterografts. Pre-operatively, over one-half (53.6%) of the patients were in New York Heart Association Functional Class IV. The overall hospital mortality was 13.8% (50 patients). The aortic valve mortality was 11.5%, the mitral valve mortality was 15.7%, and the combined procedures 14.7%. The follow-up period for hospital survivors (312 patients) extended from 2 weeks to 127.2 months, with a mean of 38.7 months or a total of 1,006 patient-years. The long term survival computed up to six years shows a 65 +/- 3.8% (standard error of the mean) for the entire group. The aortic valve group survival was 71 +/- 5.6%; the mitral valve group 60 +/- 8.2%; and the combined procedures group was 64 +/- 5.3%. Postoperative functional improvement was significant with 71.8% of the survivors in Class I and 19.6% in Class II. Based on these results, advanced age can no longer be considered a deterrant to cardiac surgery. The porcine heterograft appears to be the valve substitute of choice for this age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Human genetic technology: who shall control?

The biotechnical "revolution" has fast come upon us. It promises to produce both substantial benefits and difficult dilemmas for individuals and society. Despite the growing attention being paid to biotechnology, a major unanswered question is who shall control the development and use of the powerful array of human genetic and reproductive innovations. Should the decisions be left to individual consumers and private industry or should they be made by the government or other social institutions? After briefly reviewing development in human genetics and reproduction and describing trends toward commercialization of them, this article discusses the dilemmas these trends raise for a democratic society. It argues for the urgent need to delineate societal goals and priorities for the future and for technology assessment as early as possible in the developmental process. The article concludes by presenting some examples of the social policy problems now emerging.

Public policy implications of human genetic technology: genetic screening.

As rapid advances in human genetic research are transferred into new areas of genetic technology, questions relating to the use of these techniques will escalate. This paper examines some of the policy concerns surrounding recent developments in genetic screening. It discusses the impetus and implications of genetic screening in general, examines various applications, and analyzes the costs and benefits of screening programs currently in existence. Special emphasis is placed on whether or not screening should be considered a matter of public health and mandated on those grounds. This paper argues against any compulsory screening programs except where the disease is easily identified, applicable across social groups, and treatable. While screening services for carriers of genetic disease and prenatal diagnosis should be made available and education programs should be expanded substantially, the burden of proof for involuntary programs is placed on the proponents. There is little public health justification at this time for mandatory screening though this does not preclude future public health demands. It is argued that the goals and justification of various human genetic technologies must be examined at this time due to the rapid advancement of the research as well as the ultimate benefits promised for humankind.

KIE: Policy issues associated with different forms of genetic screening--prenatal diagnosis, phenylketonuria screening in newborns, and carrier screening programs--are examined. Criteria are suggested for cost-benefit analyses of proposed programs, and data from available studies on some genetic defects are provided. The author sees little public health justification at this time for mandatory screening; he argues against any compulsory screening programs except where the disease is easily identified and treatable. Moreover, mandatory programs should never be considered unless voluntary trial programs have proved to be socially and technically feasible.

Surgical management of the small aortic annulus. Hemodynamic evaluation.

Replacement of the aortic valve can be accomplished with ease and safety in most instances. The presence of a small aortic root, however, remains a problem in that both mechanical and stent-mounted tissue valves produce higher resting gradients in the smaller sizes. To avoid this, a technique has been developed to enlarge the aortic annulus. In a series of 253 patients undergoing aortic valve replacement, 22 required division of the aortic annulus. Extension of the incision inferiorly to the anterior leaflet of the mitral valve and a resulting separation of the annulus facilitated implantation of a larger valve. The resulting defect is obliterated with a woven Dacron patch. Hemodynamic data obtained on 12 patients who had recatheterization one to ten months postoperatively disclosed an average resting transvalvular gradient of 13.5 mm Hg. This procedure has been used successfully in combined aortic and mitral valve replacement and heart block has not occurred. Based upon encouraging follow-up studies of the Hancock glutaraldehyde-stabilized porcine heterograft, we use this prosthesis in patients with annular diameters of less than 25 mm. Our experience suggests that enlargement of the aortic annulus is necessary in a significant number of patients undergoing aortic valve replacement.

Valve replacement in patients over 70 years.

From July, 1972, to April, 1976, 54 consecutive patients over the age of 70 years underwent valve replacement at Tampa General Hospital. Twenty-one patients had isolated aortic valve replacement (Group 1), 14 had isolated mitral valve replacement (Group 2), and 19 had combined procedures that included at least 1 valve replacement (Group 3). There was 1 operative death (in Group 1), and another patient (Group 3) died three weeks post-operatively, resulting in an early mortality of 3.7%. Follow-up of the 52 hospital survivors from one to forty-one months reveals 2 additional deaths for a late mortality of 3.8%. Cardiac status improved noticeably in the surviving 50 patients. The data suggests that with current techniques, complex intracardiac procedures can be performed safely with acceptable operative mortality and a satisfactory prognostic outlook in elderly patients.

Method of managing the small aortic annulus during valve replacement.

In a series of 130 patients undergoing aortic valve replacement, 20 had the ascending aorta enlarged with a Dacron patch. Eight of these required division of the annulus with extension of the incision inferiorly to the anterior leaflet of the mitral valve. The resulting separation of the annulus allowed a larger size valve to be inserted. Glutaraldehyde-fixed procine heterografts were used in all patients having the annulus enlarged. No deaths occurred in those patients having annular enlargement, and the post-operative studies show no evidence of mitral valve dysfunction.