Biomedical subjects
Publications and source records attributed to V J DeFilippi.
A woman experienced multiple episodes of pocket erosion after placement of an implantable cardioverter defibrillator culminating in a pocket infection. The device was placed in a retroperitoneal location, and the patient has not developed further episodes of pocket erosion or infection. Interrogation of the device in this position and its subsequent replacement have been straightforward.
We characterized the responses of lymphatic vascular smooth muscle to histaminergic-receptor stimulation and blockade and explored the mechanisms underlying the histamine-stimulated release of endothelium-derived relaxing factor (EDRF). Fresh porcine tracheobronchial lymph vessel rings mounted in organ baths were stimulated by the cumulative addition of histamine or H1, H2, and H3 receptor-specific agonists in the presence or absence of receptor-specific antagonists. Histamine had a contractile effect on lymphatic vascular smooth muscle that was H1 receptor mediated. No important effects were elicited by H2- or H3-receptor stimulation. Histamine also caused the release of EDRF as demonstrated by an increase in smooth muscle tone in the absence of endothelium and after inhibition of nitric oxide synthase. This effect was strong at high concentrations of histamine and was mediated by H1-receptor stimulation. The results suggest that histamine may contribute to the regulation of lymphatic vascular smooth muscle tone under pathological conditions, an effect that may be controlled through modification of H1-receptor activity.
BACKGROUND: Prior reviews of esophageal perforation with delayed recognition have reported mortality rates as high as 66%. We performed a retrospective review of patients with nonmalignant esophageal perforation to assess the outcome of current management techniques. PATIENTS AND METHODS: Charts were reviewed of all patients who were treated for nonmalignant esophageal perforation between 1980 and 1993. They were 23 men and 10 women, mean age 49 +/- 3 years, 19 of whom were diagnosed early (< or = 24 hours) and 14 of whom were diagnosed late (> 24 hours). RESULTS: Perforations were due to instrumentation (16), operative injury (7), spontaneous rupture (4), trauma (4), and other causes (2). Pre-existing esophageal disease was identified in 23 patients (70%), including achalasia (9), stricture (7), varices (5), and other (2). Treatment included closure and fundoplication or muscle wrap (10), closure with or without pleural flap (7), resection only (7), resection and reconstruction (3), drainage only (4), and observation (2). Nonfatal complications included empyema (4), arrhythmia (3), persistent leak following attempted closure (2), and other (5). They occurred in 50% of both the early and late diagnosis groups and were of comparable severity in both. The overall mortality was 9% (3/33). Causes of death were sepsis (1) and multisystem organ failure (2). Mortality was 5% (1/19) in patients diagnosed early and 14% (2/14) of those diagnosed late. CONCLUSIONS: Current mortality rates in nonmalignant esophageal perforation are improved compared to previously published rates of 19% for all patients with the condition, 9% following early and 29% following late diagnosis (47 patients overall). We conclude that, despite a high incidence of associated complications, the survival rate following nonmalignant esophageal perforation is improving and the impact of delayed recognition is decreasing.
Lymphatic smooth muscle tone and contractility are important determinants of lymph flow. Because we have shown previously that lymph vessels exhibit endothelium-dependent relaxation similar to that identified in blood vessels, we assessed the possible role of nitric oxide as an endothelium-dependent relaxant factor in lymph vessels using porcine tracheobronchial lymph vessel rings mounted in organ baths. Isometric active tension was measured and normalized as a percentage of response to 65 mM KCl-substituted perfusate. Histamine and NE elicited contraction in all vessel rings at a concentration of 10(-5) M, and we were unable to demonstrate relaxant responses to these substances even at low concentrations. In histamine- and NE-contracted vessel rings an increase in active tension was produced by NMMA (33.9 +/- 5.4 and 26.1 +/- 5%, respectively, P < 0.0001 for each), an effect that was reversed by addition of L-arginine but not by D-arginine. Endothelial disruption reversed the effects of NMMA in histamine-contracted (16.2 +/- 4.0% increase in active tension; P = N.S. vs initial histamine response) and in NE-contracted vessel rings (11.5 +/- 1.2% increase in active tension; P = N.S. vs initial NE response). The data provide evidence that nitric oxide is an endothelium-dependent relaxant factor that regulates tracheobronchial lymphatic smooth muscle tone and is released in response to administration of contractile agonists.
The use of transcervical thymectomy in the treatment of myasthenia gravis remains controversial. We retrospectively reviewed our experience with this procedure to determine its usefulness in the management of myasthenia gravis. Fifty-three selected myasthenic patients without thymoma underwent transcervical thymectomy between 1977 and 1991. The mean age (27.5 +/- 1.5 years), duration of symptoms (2 +/- 1.0 years), and preoperative Osserman classification (13% class I, 53% class IIA, 28% class IIB, 6% class III) were consistent with previous reports. The average hospitalization was 3.0 +/- 0.3 days, but has been 1.6 +/- 0.2 days since 1987 (n = 14). There were no deaths, and no patients required mechanical ventilation for more than 24 hours. Average follow-up was 4.3 +/- 0.4 years with a range of 0 to 13 years. Eighty-one percent of patients are symptom free, and 9 of 21 (43%) are in complete remission at least 5 years postoperatively. One patient required a transsternal exploration for worsening symptoms. Clinical improvement continued over an extended period of time, and a statistically significant decrease in symptoms was evident comparing the first and sixth postoperative years. Patients were more likely to be improved or in remission if thymectomy was performed within the first year of the onset of symptoms (p < 0.05). Osserman classification, thymus histology, and patient age were not prognostic indicators. Transcervical thymectomy is effective surgical therapy for myasthenia gravis in selected patients without thymoma.
We performed morphometric and length-tension analyses comparing mesenteric and tracheobronchial lymph vessel segments to determine the potential of the latter tissue to regulate pulmonary and mediastinal lymph flow via alterations in smooth muscle tone. Fresh porcine lymph vessel rings were prepared for 1) in vitro assessment of length-tension relationships and 2) histologic preparation and measurement of smooth muscle cross-sectional area (SMA). Mesenteric and tracheobronchial optimal vessel ring lengths were 3.1 +/- 0.2 and 3.5 +/- 0.2 mm, and maximum active tensions were 1518 +/- 25 and 1703 +/- 162 mg. Smooth muscle formed indistinct layers in each tissue, and only 30% of the smooth muscle was oriented circumferentially. Stress generated by the circular smooth muscle was similar to that generated by other types of vascular smooth muscle. In 75% of mesenteric vessel rings spontaneous contractions were observed that had a mean contraction frequency of 1.7 +/- 0.2 min-1 and a mean contraction amplitude of 349 +/- 35 mg, while only 40% of tracheobronchial vessels exhibited spontaneous contractions (p < 0.001) that had a mean frequency of 0.6 +/- 0.2 min-1 (p = 0.0021) and a mean contraction amplitude of 118 +/- 10 mg (p < 0.0001). We conclude that tracheobronchial lymphatic vascular smooth muscle is capable of developing stress similar to that generated by mesenteric lymph vessels, and that spontaneous rhythmic contractile activity is qualitatively and quantitatively different in tracheobronchial than in mesenteric porcine lymph vessels. The data suggest that tracheobronchial lymph vessels are capable of regulating pulmonary and mediastinal lymph flow through intrinsic mechanisms. Such regulation may occur by alterations in vascular resistance rather than via spontaneous pumping activity.
Unlike the Nd:YAG, the CO2 laser produces well circumscribed tissue removal with little unwanted damage because of its high absorption coefficient relative to tissue water. Unfortunately, conventional quartz fibers cannot transmit wavelengths greater than three microns, well below the ten micron wavelength of the CO2 laser. Thus, fiberoptic transmission of CO2 laser requires use of exotic materials that lack the excellent properties of quartz fibers and that, in some cases, are toxic or chemically unstable. However, there are large peaks in the infrared absorption curve of water in the two to three micron region. Lasers that operate in this mid-infrared region should permit CO2-like precision of cutting, along with excellent transmission through quartz fiberoptics. Two mid-infrared lasers with a fiberoptic delivery system, the Er:YAG (2.94 micron) and the Tm-Ho-Cr:YAG (2.15 micron) have been evaluated with human colon tissue in vitro and with rabbit gastric tissue in vivo. Histologic sections reveal excellently well localized lesions with minimal underlying thermal damage. Depth of penetration is controllable and occurs in very small increments. There is little spreading of the lesions at the 24 hour mark resulting from secondary thermal damage. Based on these facts, the authors think that these lasers will be of benefit to endoscopic surgeons.
There is a need for lasers that are compatible with fiberoptic endoscopes and that provide greater cutting precision than currently can be produced by the widely used Nd:YAG (1.06 micron) laser. Recently available lasers that operate in the 2-micron region fill this need. This laser light energy can be transmitted by low OH- silica fibers and has much less tissue penetration than radiation at 1.06 micron. We have been evaluating a prototype solid state laser system that produces pulses of 2.15 microns light that is delivered by a silica based fiberoptic delivery system with negligible transmission losses. This system is based on a thulium-holmium-chromium doped YAG (Tm-Ho-Cr: YAG) rod that lases at 2.15 micron. The laser does not require cryogenic cooling, toxic gases, or custom utilities and should be practical in a clinical environment. In vivo animal testing of this laser confirms that it provides greater ablating precision than does the Nd:YAG laser at 1.06 micron.