Average Internal Diameter Research Articles

Anatomic study of the superficial perineal neurovascular pedicle: implications in vulvoperineal flap design.

Thirty superficial perineal neurovascular pedicles from 15 formaldehyde-fixed female cadavers were dissected and analyzed with the purpose of establishing the anatomic basis for the design and elevation of vulvoperineal fasciocutaneous flaps based on their anatomic elements. The average internal diameter of the superficial perineal artery was 0.53 +/- 0.2 mm, determined by means of an image analysis system. Three distinct anatomic patterns of cutaneous arterial vascularization were seen bilaterally, and two types of vulvoperineal fasciocutaneous flaps are described.

Early postoperative angiographic assessment of radial artery grafts used for coronary artery bypass grafting

Despite a revival of interest in using the radial artery as an alternative conduit for myocardial revascularization, little angiographic documentation of early postoperative results has been presented, particularly in North America. Accordingly, 60 of 150 patients who underwent coronary artery bypass with radial arteries from November 1993 to July 1995 have had postoperative cardiac catheterization at our institution. The patency rate of the radial artery grafts was 95.7% (90 of 94 grafts patent) with an average internal diameter of 2.51 mm. Four radial artery grafts showed diffuse narrowing. The patency rate of the internal thoracic artery grafts was 100% with an average internal diameter of 2.25 mm. Three of 62 grafts demonstrated diffuse narrowing. Two of 24 (7.7%) saphenous vein grafts were occluded; the average internal diameter was 3.23 mm. The internal thoracic artery, the radial artery, and saphenous vein grafts were, respectively, 7.5%, 19.5%, and 53.3% larger than the anastomosed native coronary arteries. Graft-dependent flow was found in 81.1% of the radial artery grafts. Conclusion: The results of this study demonstrate that the short-term patency rate of radial artery grafts is excellent. (J T HORAC C ARDIOVASC S URG 1996;111:1208-12)

Identification and characterization of a pore-forming protein of human peripheral blood natural killer cells.

We show here that human peripheral blood NK cells contain a pore-forming protein (PFP) with an Mr of 70,000-72,000 that assembles structural lesions (with an average internal diameter of 150-170 A) and forms functional channels. The PFP was isolated by affinity chromatography from human NK cells, using a specific anti-C9 antiserum as the immunoadsorbent. The NK cells were isolated from PBL by positive or negative selection by indirect rosetting using a panel of monoclonal antibodies directed against different NK and T cell surface antigens. PFP was identified in NK cells freshly isolated and isolated from cultured PBL, both stimulated with interleukin 2, but not in NK cell-depleted lymphocytes. In planar bilayers, the channels formed by the NK cell-derived PFP are highly voltage resistant, with most channels persisting in the open state once they have inserted into the bilayer. The unit conductances of these channels range 0.3-1 nS in 0.1 M NaCl. The channels show poor selectivity for monovalent and divalent ions. The PFP is also released from human NK cells stimulated with the calcium ionophore A23187, suggesting that this protein, like the one produced by murine CTL lines, may be similarly secreted during cell-mediated killing. Its identification in primary human NK cell cultures indicates that this protein may play an active role in NK cell-mediated killing.

Ultrasound evaluation of the normal fetal upper airway and esophagus.

Because congenital anomalies of the fetal neck may alter the normal anatomy of the upper airway, a prospective evaluation of the fetal trachea, hypopharynx, and esophagus was undertaken in 50 consecutive fetuses of 18 to 38 menstrual weeks. The cervical trachea was visualized in 47 of 50 fetuses (94 per cent) and had an average internal diameter of 2.6 mm with a range of 2 to 4 mm. The average diameter of the hypopharynx was 5.5 mm on parasagittal section (range 4-8 mm) and 7.1 mm when imaged in the coronal plane (range 4-10 mm). The configuration of the fetal hypopharynx and larynx varied with fetal respiration and swallowing in a characteristic manner. In no case was a persistent fluid collection observed in the region of the cervical esophagus, suggesting that the fetal esophagus is collapsed in the resting state.

Observations on the lateral olfactory tract of the rat.

The number and size of the axons in the later olfactory tract of the rat have been measured at several rostro-caudal levels, from material prepared for electron microscopy. Immediately caudal to the olfactory peduncle, an average of 42,000 +/- 3,000 axons were counted in the tract, while near the caudal limit of the tract an average of 32,000 +/- 2,800 axons were counted. The average internal cross-sectional area of axons measured at two levels of the tract was 1.6 +/- 1.3 mum2 and 1.1 +/- 0,9 mum2, corresponding to average internal diameters 1.4 +/- 1.3 mum and 1.2 +/- 1.1 mum, respectively. The axons in the lateral part of the tract were found to be significantly larger than those in the medial part of the tract; for one level the average cross-sectional area of axons in the lateral part of the tract was 1.6 +/- 1.0 mum2 (equivalent diameter 1.4 +/- 1,1 mum) while only 0.7 +/- 0.6 mum2 (equivalent diameter 0.9 +/- 0.9 mum) in the medial part of the tract. The thickness of the myelin sheath of the axons is generally related to axon diameter, increasing from 0.1-0.2 mum for axons 0.4 to 0.8 mum in diameter to 0.3-0.4 mum for axons greater than 2.0 mum in diameter. The ratio of the inside diameter to the outside diameter of the fiber (ratio "g") is between 0.7 and 0.8 for most axons in the lateral olfactory tract. The axons which leave the tract laterally and medially are substantially smaller than the axons within the tract (average cross-sectional area 0.55 +/- 0.35 mum2 on the lateral side) and probably are collaterals of the axons within the tract. Unmyelinated nerve processes, probably axons, were also found in the tract. Qualitative observations from light and electron microscopical material agree well with the quantitative data, and further suggest that mixing of axons from different parts of the olfactory bulb occurs in the rostral part of the tract. This is supported by experiments with injections of 3H-amino acids into localized portions of the olfactory bulb. These indicate that there is some degree of point-to-point organization in the most rostral part of the tract, but that this is lost in the caudal part of the olfactory peduncle.