Quantitative and Qualitative Assessment of Posterolateral Meniscal Anatomy: Defining the Popliteal Hiatus, Popliteomeniscal Fascicles, and the Lateral Meniscotibial Ligament.

BACKGROUND: Surgical treatment of lateral meniscal tears can be challenging due to the greater mobility of the lateral meniscus, thin capsule, and management of the popliteal hiatus. There has been a lack of quantitative assessments of the structural attachments to the posterior horn of the lateral meniscus (PHLM) to guide repairs. PURPOSE: To qualitatively and quantitatively describe the anatomy of the PHLM, popliteomeniscal fascicles, and the posterolateral capsule. STUDY DESIGN: Descriptive laboratory study. METHODS: Fourteen male, nonpaired, fresh-frozen cadaveric knees were used. The attachments of the posterolateral capsule, popliteomeniscal fascicles, and meniscofemoral ligaments to the lateral meniscus and the attachment of the meniscotibial ligament to the tibia were identified. A 3-dimensional coordinate measuring system was used to measure the relationships of these attachments to surgically relevant landmarks and their structural relationship with the lateral meniscus. RESULTS: The posterolateral capsule attachment had a confluent attachment at the superior margin of the PHLM, quantitatively attaching to the proximal 11% of the total height of the PHLM. On average, the length of the posterolateral capsule attachment to the superior surface of the PHLM was 16.7 ± 2.7 mm. The average length of the meniscotibial attachment to the posteroinferior aspect of the meniscus was 12.8 ± 3.9 mm. There was a lack of ligamentous attachments to the lateral meniscus between the lateral aspect of the meniscotibial ligament and the anterior aspect of the anterosuperior popliteomeniscal fascicle, where only popliteomeniscal fascicle and capsular attachments to the posterior meniscus were present. CONCLUSION: This anatomic study provides quantitative guidelines for the complex attachments to the PHLM. Knowledge of the quantitative descriptions of these attachments may aid in an improved intraoperative diagnosis of PHLM tears that extend to the popliteal hiatus, and further studies related to the surgical repair of the intricate attachments to the PHLM are recommended. CLINICAL RELEVANCE: The findings of this study provide the anatomic foundation for an improved understanding of the role of the meniscocapsular, meniscotibial, and popliteomeniscal fascicle attachments of the posterolateral meniscus. Understanding the differences between the lengths of the superior and inferior aspects of the popliteal hiatus will help to further refine characterization of tears extending into the popliteal hiatus and to avoid potential overconstraint of the more mobile lateral meniscus during a repair by anatomically reproducing its native structural attachments.

Quantitative and Qualitative Assessment of the Posterior Medial Meniscus Anatomy: Defining Meniscal Ramp Lesions.

BACKGROUND: Meniscal ramp lesions have been defined as a tear of the peripheral attachment of the posterior horn of the medial meniscus (PHMM) at the meniscocapsular junction or an injury to the meniscotibial attachment. Precise anatomic descriptions of these structures are limited in the current literature. PURPOSE: To quantitatively and qualitatively describe the PHMM and posteromedial capsule anatomy pertaining to the location of a meniscal ramp lesion with reference to surgically relevant landmarks. STUDY DESIGN: Descriptive laboratory study. METHODS: Fourteen male nonpaired fresh-frozen cadavers were used. The locations of the posteromedial meniscocapsular and meniscotibial attachments were identified. Measurements to surgically relevant landmarks were performed with a coordinate measuring system. To further analyze the posteromedial meniscocapsular and meniscotibial attachments, hematoxylin and eosin and alcian blue staining were conducted on a separate sample of 10 nonpaired specimens. RESULTS: The posterior meniscocapsular attachment had a mean ± SD length of 20.2 ± 6.0 mm and attached posteroinferiorly to the PHMM at a mean depth of 36.4% of the total posterior meniscal height. The posterior meniscotibial ligament attached on the PHMM 16.5 mm posterior and 7.7 mm medial to the center of the posterior medial meniscal root attachment. The meniscotibial ligament tibial attachment was 5.9 ± 1.3 mm inferior to the articular cartilage margin of the posterior medial tibial plateau. The posterior meniscocapsular attachment converged with the meniscotibial ligament at the most posterior point of the meniscocapsular junction in all specimens. Histological staining of the meniscocapsular and meniscotibial ligament PHMM attachments showed similar structure, cell density, and fiber directionality, with no qualitative difference in the makeup of their collagen matrices across all specimens. CONCLUSION: The anatomy of the area where a medial meniscal ramp tear occurs revealed that the 2 posterior meniscal attachments merged at a common attachment on the PHMM. Histological analysis validated a shared attachment point of the meniscocapsular and meniscotibial attachments of the PHMM. CLINICAL RELEVANCE: The findings of this study provide the anatomic foundation for an improved understanding of the meniscocapsular and meniscotibial attachments of the PHMM, which may help provide a more precise definition of a meniscal ramp lesion.

Effective count rates for PET scanners with reduced and extended axial field of view.

We investigated the relationship between noise equivalent count (NEC) and axial field of view (AFOV) for PET scanners with AFOVs ranging from one-half to twice those of current clinical scanners. PET scanners with longer or shorter AFOVs could fulfill different clinical needs depending on exam volumes and site economics. Using previously validated Monte Carlo simulations, we modeled true, scattered and random coincidence counting rates for a PET ring diameter of 88 cm with 2, 4, 6, and 8 rings of detector blocks (AFOV 7.8, 15.5, 23.3, and 31.0 cm). Fully 3D acquisition mode was compared to full collimation (2D) and partial collimation (2.5D) modes. Counting rates were estimated for a 200 cm long version of the 20 cm diameter NEMA count-rate phantom and for an anthropomorphic object based on a patient scan. We estimated the live-time characteristics of the scanner from measured count-rate data and applied that estimate to the simulated results to obtain NEC as a function of object activity. We found NEC increased as a quadratic function of AFOV for 3D mode, and linearly in 2D mode. Partial collimation provided the highest overall NEC on the 2-block system and fully 3D mode provided the highest NEC on the 8-block system for clinically relevant activities. On the 4-, and 6-block systems 3D mode NEC was highest up to ∼300 MBq in the anthropomorphic phantom, above which 3D NEC dropped rapidly, and 2.5D NEC was highest. Projected total scan time to achieve NEC-density that matches current clinical practice in a typical oncology exam averaged 9, 15, 24, and 61 min for the 8-, 6-, 4-, and 2-block ring systems, when using optimal collimation. Increasing the AFOV should provide a greater than proportional increase in NEC, potentially benefiting patient throughput-to-cost ratio. Conversely, by using appropriate collimation, a two-ring (7.8 cm AFOV) system could acquire whole-body scans achieving NEC-density levels comparable to current standards within long, but feasible, scan times.

A structure-based approach to drug discovery; crystallography and implications for the development of antiparasite drugs.

Advances in the life and physical sciences have enabled us to characterize the 3-dimensional structure and the biochemical or biological activity of both small and large molecules. The use of structural chemistry to assist understanding of biological activity provides information relevant to the design, development or identification of new pharmaceuticals. This structure based approach has become an important component of drug research and is in widespread use by the major pharmaceutical companies. A brief historical introduction, to convey how this area of science has reached the present stage, is given. The basis of the structural approach to understanding the chemistry of small and large molecule biological activity is outlined with an emphasis on the use of results derived from X-ray diffraction methods. Developments in other areas are discussed to emphasize the multidisciplinary nature of this research and the benefits of combining different methods. Examples of protein crystallographic studies in the area of molecular parasitology, some of which are directly relevant to antiparasite drug design, are presented. The characterization of the enzyme trypanothione reductase, a project which has benefited from many of the recent developments, is detailed. Future challenges and difficulties, both scientific and economic, are discussed.

Rational drug design: a multidisciplinary approach.

The pharmaceutical industry developed spasmodically and, in its early years, was shaped by several notable events and scientists. Paul Ehrlich, whose studies initiated the field of chemotherapy, was one of the major contributors. From early experiments on the efficacy of the biological stain methylene blue as an anti-malarial, Ehrlich realized that small molecules could be used to treat infections. Further studies identified trypan dyes and arsenical compounds as treatments of trypanosomal infection, and the arsenical compounds were found to be effective against syphilis. Ehrlich's experience of the chemical industry, in particular the chemistry of dyes, led to the realization that synthetic molecules could be medically useful and provided a powerful stimulus to pharmaceutical research.

Nonsanction seat belt law enforcement: a modern day tale of two cities.

This paper describes the implementation and evaluation of a nonsanction seat belt law enforcement program in two experimental communities of contrasting size in a state with a mandatory belt law. The main ingredients of the program were seat belt "salutes," public information and education, and limited use of inexpensive economic incentives. Driver shoulder belt use data collected before, during, and after the experimental programs, compared to similar data collected in a comparison community, showed the approach to be effective. While standard seat belt enforcement activities without incentives have been shown to be effective, many police departments, especially in smaller communities, are reluctant to make wholesale increases in seat belt citations. Although requiring some additional level of manpower and resources, a nonsanction approach to seat belt law enforcement can provide an alternate way of increasing belt use in these communities.

Functional and morphological assessment of rat aorta stored in University of Wisconsin and Eurocollins solutions.

University of Wisconsin (UW) and Eurocollins (EC) solutions are widely used for preservation of organs before transplantation. However, effect of storage solutions on vascular interface for transplant success is not known. In this study, we have used rat aorta as a model and assessed the effects of cold storage in UW and EC solutions on smooth muscle and endothelial function and the morphology. Smooth muscle and endothelial functions of the rat aorta were assessed using in vitro isometric tension measurement. Morphologic studies were done with scanning and transmission electron microscopy. No significant difference in contractile response to either norepinephrine (NE) or potassium chloride was observed between control aorta and aorta stored in UW solution for 1 hr or 24 hr. In contrast, sensitivity, but not the reactivity to NE and KCl, was increased in aorta stored in EC solution for 1 hr. If the tissues were stored in EC solution for 24 hr, both sensitivity and reactivity to NE and KCl were significantly reduced. Relaxatory response to acetylcholine, in endothelium-intact vessels were reduced in aortas stored in EC solution, but not in UW solution. The magnitude of relaxations observed in tissues stored in the EC solution for 24 hr was less than in tissues stored for 1 hr. Sodium nitroprusside elicited similar relaxatory response in endothelium-denuded control tissue and in tissues stored in UW and EC solution. Electron microscopy data revealed marked swelling of the cell, loss of mitochondria and other intracellular organelles, and striking calcium deposits after preservation of the vessels in EC for 1 or 24 hr. In aorta stored in UW solution for 24 hr, endothelial and smooth muscle cells were intact, with moderate-size vacuoles in the cytoplasm. These results suggest that the UW solution is more suitable than EC solution for short-term preoperative storage of blood vessels.

Progress in immunoassays for serum prolactin: evidence from the UK External Quality Assessment Scheme (EQAS) 1980-1989.

The quality of serum prolactin assays routinely performed by UK laboratories has been monitored in an external quality assessment scheme (EQAS) over a 10-year period, during which participation in the EQAS increased three-fold, and considerable changes in methods and standardization were introduced. The all-laboratory mean was used as the sample target value, and proved to be stable and accurate. Overall between-laboratory agreement in the clinically important range improved from a geometric coefficient of variation (GCV) of 25% to 14%. This appears to reflect the increased use of kits in place of 'in-house' assays, the more widespread availability of international standards and the absence of any marked differences in bias between the commonly used methods. Published guidelines on the clinical interpretation of prolactin values should, therefore, be widely applicable. The EQAS data indicate that, in general, the quality of performance of prolactin assays is adequate for their clinical application.

Progress and problems in immunoassays for serum pituitary gonadotrophins: evidence from the UK external quality assessment schemes, (EQAS) 1980-1988.

Trends in the quality of assays for serum gonadotrophins performed by laboratories in the UK EQAS during the 1980s are reviewed, with particular reference to the effects of the recent introduction of immunometric assays (IMA) as an alternative to radioimmunoassay (RIA). IMA gave results which were on average 17% higher than RIA for FSH, and 33% lower for LH. These bias characteristics were not entirely accounted for by differences in assay standardisation, but appeared to reflect the different isoforms of the hormones detected by the monoclonal antibodies used in the IMA. Between-laboratory agreement remained, consequently, unsatisfactory overall (geometric coefficient of variation, GCV, 20-30%), although good within method groups (GCV 10%). IMA were less vulnerable to non-specific background interference than many RIA, and could avoid interference from HCG. Some IMA were, however, vulnerable to interference from heterophilic antibodies in patients' sera. The differences between RIA and the various IMA in numerical values reported, and in their vulnerability to interferences underline the need for care in interpreting assay results.

Quality of performance of assays for serum growth hormone in the United Kingdom (UK): evidence from the UK external quality assessment scheme, 1980-1987.

The performance of laboratories in the UK External Quality Assessment Scheme for growth hormone (GH) during the years 1980 to 1987 is reviewed. The number of participating laboratories has increased steadily and is at present 67; about one half use immunoradiometric assay (IRMA) kits and the use of such kits is increasing at the expense of 'in-house' radioimmunoassays (RIAs). The consensus mean, which is used as the target value for assessing performance, has remained accurate and reproducible against this changing background. The between-laboratory geometric coefficient of variation has remained at about 18% during the period reviewed, revealing unsatisfactory between-laboratory agreement. This is in part due to poor within-laboratory performance in a small proportion of laboratories but it is also due to the negative bias of some IRMA kits. Most IRMA kits do appear, however, to provide marginally better within-laboratory precision than RIA, and are less vulnerable to non-specific interference. The laboratory interpretation of results was assessed from time to time, and was generally satisfactorily performed. In an attempt to identify the causes of poor performance, a detailed survey of assay methods and laboratory practice has been carried out; the results are described in an associated report [1].

Quality of performance of assays for maternal serum alphafetoprotein in the United Kingdom: evidence from the UK external quality assessment scheme 1980-87.

Between-laboratory agreement in the UK EQAS for maternal serum alphafetoprotein has improved steadily since 1976 and the geometric coefficient of variation is now 8 to 9% at levels of 50 to 150 kU/L. The use of a common standard and commercial assay kits appear to have contributed to this trend. Within-laboratory performance is also generally good, about 50% of participants maintain a bias of less than 5%, together with a scatter of the bias of less than 10%. These data indicate that the quality of assay performance is adequate for the requirements of screening programmes for open neural tube effects. The improvement in laboratory performance is such that between-laboratory agreement is better expressed in kU/L than as multiples of the median. Errors in interpretation of clearly normal or abnormal results appear to be rare (0.4%), and contribute little to overall false positive and negative rates. However, they assume significance as most are due to avoidable errors.

DNA conformation is determined by economics in the hydration of phosphate groups.

Mixed sequence DNA can exist in two right-handed and one left-handed double helical conformations--A, B and Z. Under conditions of high water activity the B conformation prevails. If the water activity is reduced on addition of salt or organic solvents, transformation occurs to A-DNA or, in DNAs with alternating purine-pyrimidine sequences, to the left-handed Z-DNA. In crystal structure analyses of oligonucleotides, the free oxygen atoms of adjacent phosphate groups along the polynucleotide chain in B-DNA are found at least 6.6 A apart and individually hydrated whereas they are as close as 5.3 A in A-DNA and 4.4 A in Z-DNA, and bridged by water molecules. We suggest that this more economical hydration in A- and Z-DNA compared with B-DNA is the underlying cause of B----A and B----Z transitions.

Private medical insurance in New Zealand: issues of membership and growth.

Questions concerning ownership of private medical insurance were included in a recent Department of Statistics' survey of a random sample of almost 7000 New Zealanders. The results indicated that 35% of those surveyed owned private medical insurance and such ownership was significantly related to various social, demographic and health related variables. The findings are discussed in terms of the possibilities for growth of private medical insurance and the implications of such growth for both the public and the private health care sectors.

Endocrine assessment of the subfertile male.

Sixty-three male (XY) patients attending a subfertility clinic with average sperm density under 40 million/ml were studied by testicular biopsy and multiple basal estimations of plasma LH, FSH, testosterone as well as LHRH (50 micrograms i.v.) stimulation. A further forty patients with similar sperm densities also had testicular biopsy but only single estimations of the three hormones. A single basal FSH was found to be the best discriminator of testicular histologies. Patients with testicular biopsies showing germ cell aplasia in some or all seminiferous tubules (grades 3 and 4) had significantly higher basal FSH than those with hypospermatogenesis, germ cell arrest or normal appearance (grades 1 and 2). Basal FSH also showed a linear trend rising with decreasing sperm density but only rose above the normal range when sperm densities fell below 1 million/ml. When basal FSH, testicular histology and sperm density were considered together in the whole group (n = 100), high levels of FSH accurately indicated the presence of germ cell aplasia in some or all seminiferous tubules in azoo- and oligospermic men with sperm density under 5 million/ml. Normal FSH and azoospermia is diagnostic of obstruction in the excurrent ducts, and further investigation is undertaken if surgical correction of the obstruction is contemplated. Hormone estimations are not helpful in oligospermic patients with average sperm density over 5 million/ml. On the basis of these findings it is suggested that there is little place for the LHRH test in the routine assessment of male subfertility. Testicular biopsy is indicated only in oligospermic patients with average sperm density under 5 million/ml and normal basal FSH.