Use of freshly isolated capillary endothelial cells for the immediate establishment of a monolayer on a vascular graft at surgery.

Endothelial seeding of vascular graft surfaces may lead to a less thrombogenic surface. We examined the feasibility of using microvessel endothelial cells derived from human fat for seeding purposes. Human fat was treated with collagenase for 24 minutes, washed, and purified in a Percoll gradient separation. This yielded 1.25 +/- 0.45 X 10(6) cells/gm of fat. After a 1-hour incubation on plasma-coated Dacron, 2.8 +/- 1.5 X 10(4) cells remained firmly adherent to the surface. When exposed to flow for 2 hours at a shear stress of 0 to 80 dyne/cm2, between 50% and 100% of the initially adherent cells remained adherent. Statistical analysis of this data failed to demonstrate a strong relationship between the number of adherent cells and the shear rate. Scanning electron microscopy demonstrated endothelial cells in various stages of attachment to the plasma-coated Dacron. Although most cells were still round and only focally attached to the surface, some cells were maximally flattened, forming cell-to-cell contact. Because of the high cell yield and the firm adherence characteristics, we conclude that microvessel endothelial cells may offer the possibility for confluent endothelial cell seeding of a graft at the time of surgical implantation without the need for cell culture.

Trends in selected obstetric complications from University Hospital, Kuala Lumpur, Malaysia.

Trends in selected pregnancy complications from 1969 to 1987 in a tertiary hospital in Malaysia are presented. Complications reviewed were abortion, ectopic pregnancy, anemia, hypertension, hyperemesis, antepartum and postpartum hemorrhage. Possible explanations for the observed trends were discussed, including the role of improved obstetric care and changes in the characteristics of the childbearing population. The data presented give some indication of maternal morbidity in the childbearing population served by this tertiary center and should lead to improvements in provision of services as well as in health data collection in the future.

Scoring and setting pass/fail standards for an essay certification examination in nurse-midwifery.

Examination for certification or licensure of health professionals (credentialing) in the United States is almost exclusively of the multiple choice format. The certification examination for entry into the practice of the profession of nurse-midwifery has, however, used a modified essay format throughout its twenty-year history. The examination has recently undergone a revision in the method for score interpretation and for pass/fail decision-making. The revised method, described in this paper, has important implications for all health professional credentialing agencies which use modified essay, oral or practical methods of competency assessment. This paper describes criterion-referenced scoring, the process of constructing the essay items, the methods for assuring validity and reliability for the examination, and the manner of standard setting. In addition, two alternative methods for increasing the validity of the pass/fail decision are evaluated, and the rationale for decision-making about marginal candidates is described.

Development and validation of the Nurse-Midwifery Clinical Data Set.

This paper describes the procedures used to develop and validate the Nurse-Midwifery Clinical Data Set (NMCDS), a uniform, standardized tool for the purpose of data collection about midwifery clinical practice. The instrument was developed under the auspices of the ACNM Division of Research, and it was shown to be valid for the purposes of quality assessment data collection through the use of specific instrument development and field testing procedures. These procedures included consensus panel development, expert panel review, standardization, feasibility analysis, and validation through comparison with previous outcome data and record review. The 1990 version of the NMCDS is appended to the article.

A descriptive analysis of home births attended by CNMs in two nurse-midwifery services.

This study examined outcome data from two nurse-midwifery operated home birth services in Texas. All clients who planned a home birth within the two services during 1987 comprised the population. Analyses revealed that women choosing home birth with these nurse-midwives were more frequently married, usually white, and more educated when compared with the overall U.S. childbearing population. Analgesia, episiotomy, and cesarean delivery were all found at lower rates than is reported when birth occurs in a hospital setting; complications occurred less frequently or at similar rates to those reported in the home birth literature and national statistics. Research, educational, and clinical implications of the study are discussed.

Nurse-midwives speak out on research. Results of the 1987-88 needs assessment survey, Part 2.

Part 1 of this 2 part article appeared in the preceding (January/February) issue of this journal. Results from the 1987-88 ACNM Needs Assessment Survey pertaining to research are presented. As with other topics addressed in Part 1 of the Needs Assessment Survey, subgroup analysis was conducted to determine if certain groups of CNMs had differing views and perceived needs regarding research. Survey responses were categorized to include: 1) CNM attitudes about research, 2) importance of ACNM research related services and activities, 3) use of a uniform data collection instrument, 4) CNM access to research resources, and 5) views on funding for ACNM research activities. Discussion of the implications of the results as they relate to development of the goals and objectives of the newly formed ACNM Division of Research is included.

Endocytosis and exocytosis of protein in capillary endothelium.

The transport of proteins across continuous capillary endothelium is believed to be mediated by micropinocytic vesicles which shuttle molecules between the lumenal and abluminal plasma membrane. We have studied the ability of capillary endothelial cells isolated from rat epididymal fat to endocytose fluorescently labelled ovalbumin within micropinocytic vesicles. Net association of fluorescent ovalbumin with endothelial cells reaches an equilibrium after 40 minutes of incubation. This equilibrium is presumably due to a balance between endocytosis and subsequent exocytosis of this protein. Capillaries equilibrated with fluorescent ovalbumin exhibited rapid exocytosis of this protein when it was removed from the external medium. The rate of endocytosis was concentration dependent and obeyed the kinetics expected for adsorptive phase endocytosis. High concentrations of ovalbumin stimulated the ingestion of 14C-sucrose, a marker of fluid endocytosis, suggesting that protein can affect the movement of vesicles within the endothelial cytoplasm. These results imply that capillary endothelium isolated from rat epididymal fat exhibits the ability to endocytose and subsequently exocytose protein. This demonstrates that the two components of endothelial vesicular transport or transcytosis can be observed and studied in a system of isolated capillary endothelium.

Criterion-referenced competency assessment and the national certification examination in nurse-midwifery.

The paper presents an overview of the recent change from norm-referenced to criterion-referenced score interpretation for the ACNM certification examination for entry level practice in nurse-midwifery. The advantages of criterion-referenced interpretation are presented. A successful adaptation of the Nedelsky method for the calculation of the minimum pass index, based on the identification of acceptable error, is discussed. Implications for the nurse-midwifery profession and for the national certification examination in nurse-midwifery are considered.

Nurse-midwives speak out on the ACNM. Results of the 1987-88 Needs Assessment Survey, Part 1.

This article presents the purposes and methods of the first Needs Assessment Survey of all nurse-midwives who have been certified by the ACNM. A detailed summary of the general results of the survey is provided, and includes the perceptions of respondents about the ACNM organizational structure, goals, leadership, and services. Analyses of differences in response based on such variables as membership status, minority status, years since certification, level of educational preparation, work setting, and region of residence are also presented. The article concludes with a discussion of the implications for the nurse-midwifery profession. Part 2 will appear in JNM 34:2.

Rapidly-frozen, cultured, human endothelial cells: an ultrastructural and morphometric comparison between freshly-frozen and glutaraldehyde prefixed cells.

Cultured, human endothelial cells from the iliac vein were divided into two groups for rapid-freezing using liquid helium in a Heuser-type cryopress freezing machine. The first group of cells was prefixed in buffered 2% glutaraldehyde solution whereas the second group was freshly-frozen. Following freeze substitution and embedding, morphometric analysis was carried out on thin sections of groups of endothelial cells. Measurements showed that glutaraldehyde prefixation significantly increases the numerical and volume densities of the vesicles compared to those of the freshly-frozen cells. However, the fact that no significant increase was demonstrated either in the numerical or volume densities of the caveolae, and that no significant change was observed in the ratio of the cell perimeter to area, suggests that the membrane source for these extra vesicles is internally generated. Studies are currently under way to identify the source of this membrane.

Initial adherence of human capillary endothelial cells to Dacron.

Successful endothelialization of vascular grafts by seeding with endothelial cells (EC) at implantation is related to the number of EC which initially adhere to the graft. Using an in vitro system we examined the initial adherence of EC from human perinephric fat capillaries to woven Dacron that was either unmodified or precoated with several substrates. We studied capillary EC because they have not been investigated as a source of EC for graft seeding, although transinterstitial capillary ingrowth is one possible mechanism for spontaneous graft endothelialization. EC were isolated using collagenase and characterized morphologically and functionally including positive factor VIII-related antigen staining. EC were studied at three phases in culture: (A) primary EC with no subcultivations (EC-0); (B) EC after two subcultivations with trypsin (EC-2); and (C) EC after 10 subcultivations with trypsin (EC-10). EC were seeded onto graft material at a density of 10(5) cells/cm2 (100% confluence) and examined for cell counts and morphology after one day in culture by light and electron microscopy. Results are as follows: (table; see text) The conclusions are: (1) All capillary EC demonstrated adherence to Dacron, but this initial adherence was strongly influenced by graft pretreatment with collagen or plasma. (2) Serially subcultivated EC (EC-2 and EC-10) had significantly higher initial adherence to pretreated Dacron compared to the primary cells (EC-0) (P less than .05). This suggests that briefly cultured and subcultivated EC have superior initial adherence characteristics to treated dacron compared to primary EC with no subcultivations. (3) Fat capillary EC are easily procured and cultured and provide a rich source of human EC for endothelializing vascular prostheses.

Use of an endothelial monolayer on a vascular graft prior to implantation. Temporal dynamics and compatibility with the operating room.

The temporal sequence of events was examined from initial contact of endothelial cells (ECs) to Dacron until the establishment of a monolayer. Cultured human adult ECs were radiolabeled, seeded onto Dacron, and adherence was quantified after vigorous washing. Firm adherence of 70% of the seeded ECs was seen by 2 hours to untreated Dacron, by 30 minutes to Dacron pretreated with a combination of interstitial type I/III collagen and an amnion-derived basement membrane (Type IV) collagen surface, and by 10 minutes to plasma-coated Dacron. Parallel samples were examined morphologically by scanning electron microscopy (SEM) to evaluate the adherence of ECs to surfaces. ECs seeded onto plain Dacron exhibited limited adherence, while cells on plasma-treated Dacron exhibited limited cell-cell associations. On basement membrane-treated Dacron, by 30 minutes the ECs exhibited a flat attenuated morphology, completely covering the graft surface. This time-frame is compatible with most vascular procedures, making an immediately endothelialized graft feasible.